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Nutrition
February 6, 2011
From a nutrition perspective, we can look back at the 80’s as the low-fat decade where consumption of as little dietary fat as possible was believed to be the key to weight management. The 90’s saw a backlash to this notion and hence became the low carb era where steak and eggs became standard fare. Today, consumers are understandably confused as to the best way to eat. Meanwhile, the low carb vs. high carb debate continues to rage on.
A recent ABC news article titled May the Best Calorie Lose explored the subject of whether certain eating styles may have a bearing on weight loss, above and beyond simply consuming fewer calories than you expend. While the article does make for good theater, both sides in the debate seem to be missing the boat.
On a basic level, it *is* calories that count. This is consistent with Newton’s First Law of Thermodynamics, which states that energy can neither be created or destroyed, only transferred from one form to another. Thus, if you consume more calories than you expend, you will gain weight; if you expend more calories than you consume, you’ll lose weight. Mark Haub’s recent experiment with the Twinkie Diet is ‘Exhibit A’ in support of the concept. Simple, right? Well, not exactly…
In vivo (i.e. within living subjects), there are mitigating conditions by which the body can become either more or less efficient at utilizing calories for energy production. So while over the short term you will lose weight simply by cutting calories below maintenance levels, over the long term the types of foods you eat will indeed have an effect on weight management. Unfortunately, those in the “low carb” and “high carb” camps are both off-base in their focus on the subject.
Fact is, neither carbs nor fat are inherently “evil.” Rather, it’s the *types* of carbs and fat that have the greater effect on weight maintenance. There is a big difference between consuming a slice of Wonder bread and a bowl of steel cut oatmeal. Yes, both are carbohydrates, but their effect on the body couldn’t be more different. Similarly, there is a big difference between consuming salmon versus bacon, despite both containing copious amounts of dietary fat (hint: the omega-3 fats in salmon are heart healthy and highly bioactive compared to the saturated fat in bacon). This is why it is silly for the nutritionist in the above article to cite a study comparing consumption of candy versus peanuts, and claim that it supports a low carb lifestyle. It’s an apples to oranges argument.
Yet the most important aspect of diet which seems to escape many nutritional professionals is the effect of protein consumption on body composition–irrespective of carbs or fat. Pure and simple, protein is the most important nutrient in your diet. For one, eating protein creates a sensation of satiety (i.e. fullness) that leaves a person feeling satisfied after a meal. The prevailing body of research studies show that protein induces a greater effect on satiety than either carbs or fat (1, 2, 3). It is believed this may be due to the effects of protein on various hormones involved in signaling the brain as to whether or not you are full (4, 5).
Proetin also has a much greater thermic effect than either carbs or fat. This phenomenon, called the thermic effect of food (TEF), describes the energy cost associated with digestion. The TEF of protein is approximately 25-30% of calories while that of carbs is generally determined to be less than 10%. Dietary fat has a negligible thermic effect, depending on the type of fat consumed. Studies show that because of the TEF, diets higher in protein exert a larger effect on energy expenditure than diets lower in protein, and can even help to attenuate weight gain during times of overfeeding (6).
Lastly, and perhaps most importantly, protein consumption helps to preserve lean mass (read: muscle tissue) during dieting. For every pound lost on a diet the typical “normal” protein diet (at levels prescribed by the RDA), approximately 1/3 of a pound comes from the breakdown of muscle tissue. Remember that muscle is metabolically active tissue and its loss will inevitably cause a slowing of your metabolism and subsequent weight regain. The only way to counteract this occurrence is by consuming extra protein. Keeping protein intake high helps to preserve lean tissue, preventing the negative consequences of muscle wasting (7, 8, 9).
So how much protein should you consume. The RDA for protein intake is 0.8 grams/kilogram of body weight. By all accounts, this is too low, even for couch potatoes. Recent research shows that elderly individuals lose functional ability when following the RDA guidelines resultant to losses in lean mass (10). Studies show that physically active individuals need approximately 1.4 to 2.0 grams per kilogram of body weight, depending on types and intensity of exercise (11). My general recommendation is to round this off and consume approximately one gram of protein per pound of ideal body weight (i.e. the weight you aspire to being when you are at your leanest). This provides a margin of safety, ensuring you never fall into negative nitrogen balance. And in case you’re worried about negative health effects, rest easy. As long as you have healthy kidney function, research has debunked the claims that higher protein diets will put you on dialysis.
Stay Fit!
Brad
1. Leidy HJ, Armstrong CL, Tang M, Mattes RD, Campbell WW. The influence of higher protein intake and greater eating frequency on appetite control in overweight and obese men. Obesity (Silver Spring). 2010 Sep;18(9):1725-32.
2. Westerterp-Plantenga MS, Rolland V, Wilson SA, Westerterp KR. Satiety related to 24 h diet-induced thermogenesis during high protein/carbohydrate vs high fat diets measured in a respiration chamber. Eur J Clin Nutr. 1999 Jun;53(6):495-502.
3. Hill AJ, Blundell JE: Macronutrients and satiety; The effects of a high protein or high carbohydrate meal on subjective motivation to eat and food preferences. Nutr Behav 3:133–144, 1986.
4. Leidy HJ, Mattes RD, Campbell WW. Effects of acute and chronic protein intake on metabolism, appetite, and ghrelin during weight loss. Obesity (Silver Spring). 2007 May;15(5):1215-25.
5. Bowen J, Noakes M, Trenerry C, Clifton PM. Energy intake, ghrelin, and cholecystokinin after different carbohydrate and protein preloads in overweight men. J Clin Endocrinol Metab 2006; 91: 1477–148
6. Halton TL, Hu FB. The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review. J Am Coll Nutr. 2004 Oct;23(5):373-85. Review.
7. Leidy HJ, Carnell NS, Mattes RD, Campbell WW. Higher protein intake preserves lean mass and satiety with weight loss in pre-obese and obese women. Obesity (Silver Spring). 2007 Feb;15(2):421-9.
8. Blackburn, GL. Protein requirements with very low calorie diets. Postgrad Med J. 1984;60 Suppl 3:59-65.
9. Piatti PM, Monti F, Fermo I, Baruffaldi L, Nasser R, Santambrogio G, Librenti MC, Galli-Kienle M, Pontiroli AE, Pozza G. Hypocaloric high-protein diet improves glucose oxidation and spares lean body mass: comparison to hypocaloric high-carbohydrate diet. Metabolism 1994 Dec;43(12):1481-7
10. Campbell WW, Trappe TA, Wolfe RR, Evans WJ. The recommended dietary allowance for protein may not be adequate for older people to maintain skeletal muscle. J Gerontol A Biol Sci Med Sci. 2001 Jun;56(6):M373-80.
11. Campbell B, Kreider RB, Ziegenfuss T, La Bounty P, Roberts M, Burke D, Landis J, Lopez H, Antonio J. International Society of Sports Nutrition Position Stand: Protein and Exercise. J Int Soc Sports Nutr. 2007;4:8
Nutrition
January 30, 2011
Perhaps you’ve seen the headlines: Twinkie diet helps nutrition professor lose 27 pounds. In case you missed it, Mark Haub, a professor of human nutrition at Kansas State University, conducted a weight loss experiment. The premise: could he lose weight on a diet consisting primarily of junk food? The results: 27 pounds lighter over the course of ten weeks!
Surprised? You shouldn’t be. As I’ve noted in previous posts, Haub simply followed Newton’s First Law of Thermodynamics by consuming fewer calories than he expended. Specifically, he cut his calories from about 2600 calories per day to less than 1800–a daily deficit of 800 calories. Given that there are approximately 3500 calories in a pound of fat, do the math and it all adds up. What might be somewhat surprising is that in addition to losing weight, Haub actually saw an improvement in his lipid profiles, with a 20% drop in LDL (i.e. the “bad” cholesterol) and a 39% reduction in triglycerides. Pretty impressive, huh?
Now before you run out to your local 7-11 and stock up on Twinkies and Ho-Ho’s, a couple of things must be taken into account. For one, based on body fat estimates provided by Haub, he lost about 6 pounds of muscle over the diet period. Given that muscle is metabolically active tissue, his metabolic rate would have crashed, hastening the onset of a weight loss plateau. For another, the excessive intake of sugars undoubtedly sent his blood sugar levels skyrocketing, increasing hunger. Taken together, these factors would make it increasingly harder for him to sustain weight loss over time and likely result in the dreaded rebound effect where body fat is regained at an accelerated rate.
The take home message here is that any diet will help you to lose weight in the short-term provided there is a caloric deficit. Long-term weight maintenance, however, requires a change in lifestyle. This involves adopting a “metabolically friendly” nutritional regimen combined with regimented resistance training. Central to this approach is making sure that protein intake is maintained at approximately 1.6 to 2.0 grams per kilogram of body weight (slightly less than 1 gram per pound of body weight). Studies repeatedly show that protein intake is the most important determinant of body composition, particularly during times of caloric restriction (i.e. when you are “dieting”). Consuming adequate protein attenuates muscle loss while enhancing satiety–essential factors in achieving lasting weight loss.
Bottom line: take a sensible with your nutrition. If weight loss is desired, make sure you take in fewer calories than you expend. Science tells us it’s the only way to lose weight. What’s more, focus on eating protein-rich foods that furnish your body with the necessary raw materials for building lean tissue. Despite what you may have been led to believe, protein is the most important dietary nutrient, hands down. I’ll address the research on the topic in an upcoming post. Stay tuned…
Stay Fit!
Brad
Nutrition
December 4, 2010
Nutritionists generally promote the belief that alcohol is detrimental to maintaining low body fat levels. “Lipogenic” (fat promoting) is a term often used. This is what I was taught in my nutritional coursework at both the undergraduate and at the graduate level, and what continues to be perpetuated in the texts I use as a nutritional professor. A closer look at the research, however, shows that it’s not quite as simple as you may think.
Studies consistently show that alcohol intake blunts fat burning (1, 2, 3). This clearly suggests that drinking is taboo for anyone who aspires to get lean, right? On the other hand, those who consume a moderate amount of alcohol don’t seem to be any heavier than those who are teetotalers. What gives?
In an editorial appearing in the American Journal of Clinical Nutrition some years ago, Eric Jequier wrote about this apparent paradox. Jequier concluded his paper by stating: “How can we resolve the above-mentioned paradox? Is it really true that alcohol intake is associated with increased energy intake in daily life? Have we sufficiently taken into account the influence of confounding factors such as underreporting of energy intake in obese subjects and the frequent association between smoking and alcohol intake? Clearly, the complex relation between alcohol intake and body weight regulation needs to be studied further by using a combined approach of epidemiology, psychophysiology, and metabolic investigations.” Amen!
Based on my early studies, I was a staunch advocate for strictly limiting alcohol intake in those who wanted to reduce body fat. It seemed consistent with the research. More recently, however, an extensive review of the literature as well as ongoing anecdotal evidence has caused me to temper my stance. Here’s the bottom line: Unless you are physique athlete in the last few weeks before a competition, the net effect of moderate consumption (1 to 2 drinks a day) on body composition will be negligible. What’s more, emerging evidence shows potential health benefits, particularly for the cardiovascular system, associated with moderate intake. All things considered, the risk/reward is actually pretty good.
So here’s my take: a drink or two a day is generally fine (and perhaps beneficial from a health perspective) for the majority of people provided overall caloric balance is not increased. But the last part of the sentence is key here. Consider the caloric content in some popular alcoholic beverages: a margarita has 600 calories, a martini 250, and a beer 150. The calories can really add up quickly. What’s more, consumption of alcohol has been shown to increase appetite (4), and tends to supplement rather than displace calories (5). Ultimately, if you take in more calories than you expend, you will gain weight. And binge drinking clearly has a detrimental effect on body composition–if you pound down a slew of drinks, you will seriously impair fat loss.
Martin Berkhan did a nice job simplifying the research on the topic in a recent blog post. If you’re interested in the science, I’d encourage you to give it a read.
Stay Fit!
Brad
1) Suter PM, Schutz Y, Jéquier E. The effect of ethanol on fat storage in healthy subjects. N Engl J Med 1992;326:983–7
2) Murgatroyd PR, Van de Ven MLHM, Goldberg GR, Prentice AM. Alcohol and the regulation of energy balance: overnight effects on diet-induced thermogenesis and fuel storage. Br J Nutr 1996;75:33–45.
3) Sonko BJ, Prentice AM, Murgatroyd PR, Goldberg GR, van de Ven ML, Coward WA. Effect of alcohol on postmeal fat storage. Am J Clin Nutr 1994;59:619–25.
4) Westerterp-Plantenga MS, Verwegen CRT. The appetizing effect of an aperitif in overweight and normal-weight humans. Am J Clin Nutr 1999;69:205–12.
5) De Castro JM, et al. Moderate alcohol intake and spontaneous eating patterns of humans: evidence of unregulated supplementation. Am J Clin Nutr. 1990 Aug;52(2):246-53.
Nutrition
November 6, 2010
No question about it, protein is the most important macronutrient in your diet. But many people are confused as to how much protein they really need to consume. Here’s the lowdown…
If you go by the recommended dietary allowance (RDA) espoused by the Department of Agriculture, protein intake should equate to a little less than 0.8 grams per kilogram of bodyweight. The RDA, however, has a major flaw in its design: it bases protein requirements on the average couch potato. While this is fine if you want to be an average couch potato, it has little relevance if you are a hard training fitness enthusiast. In truth, those who aspire to optimize body composition require significantly more protein than what is prescribed in the RDA.
For active individuals, especially those involved in strength training regimens, studies have consistently shown optimal intake to be about 1.6 to 2.0 grams of protein per kilogram of bodyweight (roughly double the RDA). The reasons are twofold: First, during exercise, amino acids are oxidized for fuel at an accelerated rate. Depending on the intensity and duration of training, these amino acids can supply up to 10 percent of the body’s energy needs. What’s more, the stresses associated with physical activity cause an increased breakdown of body proteins, leaving the body in a catabolic state. The only way to reverse these effects and promote an anabolic environment is by consuming additional dietary protein, over and above RDA guidelines. Abide by the RDA and you’ll surely be in a negative nitrogen balance (i.e. your body is breaking down proteins at a greater rate than it’s synthesizing them).
A protein-rich diet also confers specific metabolic benefits. For one, a large percentage of calories from protein are burned off in the digestion process—a phenomenon called the thermic effect of food (TEF). Of all the macronutrients, protein has the highest thermic effect, burning off approximately 25 percent of the calories consumed. In comparison, only about 8 percent of the calories from carbs are burned off in digestion; the thermic effect of dietary fat is minimal. When the TEF is factored into a mixed meal, higher intakes of protein can as much as double post-prandial thermogenesis (i.e. the number of calories burned after eating), leaving fewer calories available to be stored as fat.
Further, protein tends to curb appetite. During its digestion, protein potentiates the secretion of a hormone called cholecystokinin (CCK), which acts to suppress the body’s hunger mechanisms. These satiety-inducing effects are pronounced, lasting several hours after a meal. And when appetite isn’t driven by hunger, food choices can more easily be made based on rationale rather than impulse. This is why studies have consistently shown that when people are left to make their own nutritional decisions (called an ad libitum diet), those who consume high amounts of protein take in significantly fewer calories than those who don’t.
A higher protein intake is especially important when you are restricting calories (i.e. the goal is weight loss). During stringent dieting, there is a tendency for your body to break down protein stores into glucose (through a process called gluconeogenesis) so that the brain and other tissues have adequate fuel. Since skeletal muscle is not necessary for sustenance (as opposed to the internal organs and other protein-based tissues), it is the primary bodily tissue to be cannibalized. The only way to counteract this occurrence is by consuming extra protein. Keeping protein intake high helps to preserve lean tissue, preventing the negative consequences of muscle wasting.
Taking all factors into account, my general recommendation is to consume approximately one gram of protein per pound of ideal bodyweight (i.e. the weight you aspire to being when you are at your leanest). This provides a margin of safety, ensuring you never fall into negative nitrogen balance. And in case you’re worried about negative health effects, rest easy. As long as you have healthy kidney function, research has debunked the claims that higher protein diets will put you on dialysis. For more info, read my article High Protein Diets: Myths, Half-truths and Outright Lies.
Stay Fit!
Brad
Nutrition
September 11, 2010
For all the coffee bashers who continue to perpetrate the idea that a cup of java is health hazard, here is yet another study to refute such assertions. Misik and colleagues (1) investigated the impact of filtered coffee on oxidative damage. 38 subjects were given either 800 ml of coffee or water for five days using a crossover design (meaning subjects received both conditions). The results? Coffee gets a big thumbs up, reducing formation of oxidized purines (a marker of DNA damage) by 12.3%. Researchers concluded that “coffee consumption prevents endogenous formation of oxidative DNA-damage in human.” These findings are consistent with other research. Better yet, evidence suggests benefits can be seen with as little as a single cup of coffee a day.
Understand that coffee is a rich source of antioxidants, which help to fight free radicals that can damage bodily tissues. Scientists are just beginning to explore the many health-related benefits that coffee may confer. The belief that it is detrimental to wellness when consumed responsibly is clearly misguided (excluding a limited number of people who may be contraindicated from consuming caffeinated beverages as advised by a physician).
Also, let’s put to rest the contention that caffeine is a diuretic that will leave you dehydrated. In an extensive review on the subject, Maughan and Griffin (2) found no evidence that caffeine had a negative effect on fluid balance. The authors went on to conclude that the overwhelming body of research offers “no clear basis for refraining from caffeine containing drinks in situations where fluid balance might be compromised.”
Stay Fit!
Brad
1) Mišík M, Hoelzl C, Wagner KH, Cavin C, Moser B, Kundi M, Simic T, Elbling L, Kager N, Ferk F, Ehrlich V, Nersesyan A, Dušinská M, Schilter B, Knasmüller S. Impact of paper filtered coffee on oxidative DNA-damage: Results of a clinical trial. Mutat Res. 2010 Aug 13. [Epub ahead of print]
2) Maughan RJ, Griffin, J. Caffeine ingestion and fluid balance: a review. Journal of Human Nutrition and Dietetics 16(6): 411–420, 2008.
Nutrition
August 26, 2010
Interesting blog post from the American Council on Exercise titled How much difference is there in nutritional value between fresh and frozen fruits and vegetables?. The article does a good job relating some of the misconceptions about the differences between fresh and frozen produce. Give it a read and you’ll see that, depending on where and when you buy your produce, fresh is not necessarily best.
It also should be noted that the same principles apply to purchasing seafood. Realize that any fish caught at sea is most likely kept frozen on the boat, sometimes for several days. The fish is then defrosted and often spends several more days in transit before appearing on the store display shelf as “fresh” fish. Bottom line: unless you are catching the fish yourself or buying it directly from a fisherman who has just returned to port after a day’s catch, you’re probably better off buying the fish frozen. As with fruits and veggies, frozen fish uses a process of flash freezing at temperatures below 40 degrees Celsius that maximally seals in nutrients. Simply thaw out the fish in the refrigerator a day before you’re ready to cook it and you’ll have a nutritious, great tasting meal!
Stay Fit!
Brad
Nutrition
June 30, 2010
Post-workout nutrition is one of the hottest topics in the fitness field. I’ve discussed this topic in a previous post. But what about before training? Is there anything special you should eat?
The main nutritional goal pre-workout is to supply adequate energy for your muscles and brain during training. This makes carbohydrate consumption essential. Carbs are stored as glycogen in your liver and muscles. Since high intensity exercise utilizes energy at a very fast rate, the body can’t supply enough oxygen to harness fat as a fuel source. Thus, it relies on its glycogen stores, which don’t require oxygen to be broken down for energy.
By taking in carbs before exercise, you ensure that you’re body’s glycogen stores are fully stocked. With a ready supply of glycogen, your muscles can access energy on demand. In this way, you’re able to go all-out in your training efforts, extending performance without “hitting the wall.”
Protein should also be included in your pre-workout meal. Although it doesn’t contribute much in the way of energy, consuming protein prior to exercise has both anabolic and anti-catabolic effects. Recent research has shown that, by providing a steady stream of amino acids at the onset of training, you maximize their delivery to working muscles and thereby attenuate the breakdown of muscle tissue during your workout. Moreover, you significantly increase muscle protein synthesis in the first hour after exercise, priming the body for anabolism.
The consumption of fat, on the other hand, should be kept to a minimum in the pre-exercise period. Fat delays gastric emptying, thereby prolonging the time it takes foods to digest. If food sits in your stomach during exercise, there is an increased likelihood of gastric problems including cramping, nausea and reflux.
For best results, try to consume your pre-workout meal approximately two to three hours before training. Allowing a couple of hours between the end of your meal and the onset of exercise will ensure that the majority of your meal is digested and help to prevent gastric upset. Stick with slow burning carbs and lean sources of protein. Oatmeal and egg whites, tuna on multi-grain bread, lean steak and yams, chicken breast and brown rice are all terrific options. Total calories should be about the same as in one of your “regular” meals. This will provide adequate fuel without bogging down your stomach.
If you aren’t able to consume a full meal in the prescribed timeframe, opt for a piece of fruit within a half-hour of your workout. Due to a high concentration of fructose, fruits are low on the glycemic index. This is significant because it keeps insulin levels stable, thereby preventing the potential for rebound hypoglycemia—a condition that can result in lightheadedness and fatigue. At the same time, fruits provide a valuable source of fuel during exercise, improving your capacity to train.
Ideally, the piece of fruit should be combined with a whey protein drink. Whey is a “fast acting” protein, meaning it’s rapidly absorbed into circulation. This expedites the flow of amino acids to your muscles without having an appreciable impact on digestion. Aim for about one-tenth of a gram of whey per pound of body weight (i.e. a woman weighing 120 pounds would need about 12 grams of whey) mixed in a water-based solution.
The pre-exercise period is also a great time to have a cup of coffee. Caffeine acts on the sympathetic nervous system to increase catecholamine (i.e. epinephrine and norepinephrine) production. Among their diverse functions, catecholamines mobilize fatty acids from adipocytes (i.e. fat cells), allowing them to be utilized for energy. And since exercise increases caloric expenditure, the body can make immediate use of these fatty acids to fuel your muscles. At the very least, it can help to expedite exercise-induced fat loss.
Stay Fit!
Brad
Nutrition
June 8, 2010
If you’ve ever bought a meal replacement bar, you’re probably familiar with the the term net impact carbs. Simply stated, net impact carbs refers to the amount of carbs in a product that promote an insulin response. As you may know, carbs can raise blood sugar levels, causing insulin levels to spike.
Why is this important? Well, high blood sugars levels cause the pancreas to secrete insulin in large amounts. Insulin is a storage hormone. While its primary purpose is to neutralize blood sugar, it also is responsible for converting sugars into body fat as well as inhibiting the conversion of stored fat into energy. When carbohydrates are ingested, the pancreas secretes insulin to clear blood sugar from the circulatory system. Depending on the quantities and types of carbs consumed, insulin levels can fluctuate wildly, heightening the possibility of fat storage.
To mitigate insulin response, many nutriceuticals substitute high-glycemic carbs with alternative carb-based nutrients called sugar alcohols (also called polyols), which have a negligible impact on blood sugar. Theoretically, by limiting carbohydrates that increase insulin levels (i.e. net impact carbs), you can minimize the deleterious effects of insulin and promote better weight management.
But while it’s true that carbohydrates that raise blood sugar can be detrimental to maintaining low body levels, the concept of net-impact carbs isn’t as clear cut as it may seem. Generally speaking, meal replacement bars also contain a combination of protein, fat and/or fiber. This slows digestion and moderates glycemic response, thereby reducing the fat-storing effects of insulin.
On the plus side, the sugar alcohols (such as maltitol, mannitol, sorbitol, Xylitol, and HSH) used as replacement carbs are not able to be fully absorbed by the body and thus are lower in calories than “standard” carbohydrates. They contain between two to three calories per gram as opposed to the four calories per gram in glucose, fructose and galactose (glycerol, a sugar alcohol found in many bars due to their propensity to keep foods moist and improve shelf life, also contains four calories per gram). Since calories do count and ultimately have the greatest effect on whether you gain or lose body fat, this is a benefit for those seeking to lose weight.
Bottom line: Nutrition is a complex subject and it’s important to understand that many factors come into play when designing a regimented eating plan. From an insulin standpoint, the overall effect of net impact carbs on body composition will be negligible. Significantly more important is the nutritional content and caloric density of the food source.
Stay Fit!
Brad
Nutrition
May 26, 2010
Make no mistake, what you eat following exercise can have a major impact on your results. After an intense workout, your body is in a catabolic state. It has spent a good deal of its stored fuels (including glycogen and amino acids) and in most cases sustained damage to its muscle fibers. The good news is that this presents a window of opportunity for anabolism. By consuming the proper ratio of nutrients during this time, not only do you initiate the rebuilding of damaged tissue and energy reserves, but you do so in a supercompensated fashion that fosters improvements in both body composition and exercise performance.
One of the primary goals post-exercise is to replenish glycogen (stored carbohydrate). Because glucose is depleted during training, your muscles and liver are literally starved for carbohydrate. In response, several adaptations take place. For one, the transporters responsible for bringing glucose into muscle cells (called GLUT4) become much more active. For another, your body stimulates the activity of glycogen synthase—the principle enzyme involved in promoting glycogen storage. The combination of these factors facilitates the rapid uptake of glucose into muscles, allowing glycogen to be replenished at an accelerated rate.
Carbohydrates are best taken in liquid form and should come from simple, high-glycemic sources. This is one instance where it is beneficial to spike insulin levels. You see, insulin has both anabolic and anti-catabolic functions, helping to increase protein synthesis, decrease protein breakdown, and shuttle glycogen into cells. And this is one instance where elevated insulin won’t promote increases in body fat. Because your muscles are in a depleted state, nutrients will tend to be used for lean tissue purposes rather than fat storage.
A combination of glucose and fructose is ideal, here. In addition to eliciting an insulin response, glucose is the primary source of muscle glycogen. Fructose, on the other hand, preferentially replenishes liver glycogen (glucose is of limited utility to the liver, a phenomenon called the “glucose paradox”). Thus, the two types of sugar work synergistically to restock the body’s glycogen stores.
Grape, apple, and cranberry juices are generally good choices since they have a high ratio of glucose to fructose. A good starting point is to consume ½ gram of carbs per pound of “ideal” bodyweight. Thus, if your goal weight is 120 pounds, then you’d consume 60 grams of carbs. For those who are “carb sensitive,” cut this amount back to ¼ gram of carbs per pound of body weight. Over time, assess how your body responds and modify the amount based on individual response.
The other main nutritional objective post-workout is to supply sufficient protein for tissue repair. If protein intake is inadequate following training, recuperation is shortchanged and results are comprised.
Protein should preferably be in the form of a high-quality protein powder. The idea is to saturate your muscles in amino acids, providing them with the raw materials to facilitate recovery. When amino acids are consumed following training, protein synthesis is increased more than threefold over fasting conditions, optimizing the development of lean muscle tissue.
A fast-acting protein such as whey works best. Because it is rapidly assimilated, whey reaches your muscles quickly, thereby expediting repair. And since your muscles are primed for anabolism, virtually all of the protein will be utilized for rebuilding with little wastage. Recent evidence suggests that combining whey with some casein can have even greater effects on protein synthesis, but this needs further study. Aim for ¼ gram of protein per pound of body weight, mixing the powder directly into your post-workout drink.
Refrain from consuming fats following your workout. Dietary fat slows gastric emptying, delaying the time that glucose and amino acids can enter the bloodstream and be used by the body. And if nutrients don’t reach your muscles in a timely fashion, results will suffer.
Caffeinated beverages should also be avoided during the post-workout period. Caffeine interferes with post-exercise insulin action, thereby impairing your body’s ability to replenish glycogen stores and utilize protein for muscular repair. Hence, wait at least a couple of hours after your workout before indulging in that cup of coffee or tea.
Ideally, you should consume your post-workout meal as soon as possible after training. The quicker you feed your body, the more it sops up nutrients and utilizes them for repair. Since blood flow is increased from the exercise bout, the delivery of protein and carbs is enhanced, resulting in greater muscle protein synthesis. But even if you are unable to consume your post-workout meal immediately upon cessation of training, all is not lost. The window of opportunity lasts for at least a couple of hours following exercise so just make sure you take in the specified nutrients as soon as you can.
Stay Fit!
Brad
Nutrition
May 14, 2010
You may have seen commercials for a product called Vitamin Water. Vitamin Water is marketed as a “great-tasting, healthy enhanced water that is packed with nutrients” as well as “…providing a perfect complement to everyone’s less-than-perfect diet…” However, a look at the ingredients reveals otherwise…
Vitamin Water is not simply water with added vitamins. It contains 50 calories of sugar, which come in the form of crystalline fructose. Now 50 calories of sugar by itself is generally no big deal, but the calories definitely add up if you consume multiple bottles of the product–which apparently many people do. Moreover, fructose has been shown to be lipogenic, meaning it preferentially promotes fat storage. Given that the body has limited ability to store fructose as glycogen (only the liver can store fructose–muscles lack an enzyme critical for storage), gulping down several drinks could easily result in an increase in body fat.
More to the point, you would be much better served by taking a multi-vitamin/mineral complex to satisfy any additional micronutrient needs not met by the foods in your diet. You can get a month’s worth of vitmains and minerals from a one-a-day supplement for what you would pay for a single bottle of Vitamin Water!
Bottom line: Save your money on Vitamin Water–the costs outweigh the benefits. If you want to add taste to your water, squeeze in some lemon or lime. It’ll be better for your waist line and your wallet.
Stay Fit!
Brad
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