For decades, health "authorities" have taught us that a diet low in fat and high in starch (e.g., USDA Food Pyramid)
promotes fat loss
decreases the risk of chronic diseases
. It should be noted, however, that there's little, if any, scientific evidence supporting this notion. In fact, the current epidemic of diabetes and obesity has been accompanied by a significant
decrease in fat consumption
increase in carbohydrate consumption
. Thus, alternative dietary approaches are clearly needed, especially for
already know what science is now showing. When one wants to
MAXIMIZE fat loss
building muscle mass
, a very-low carbohydrate/high-protein diet is the way to go. Also, purported adverse effects of such diets are greatly exaggerated, at least in the short-term. This article refutes some enduring very-low-carbohydrate diet-related urban legends, reviews studies examining the effects of very-low-carbohydrate diet interventions on body composition, and provides some dietary guidelines for those who want to cut all the extra fat, while simultaneously increasing muscle mass.
Very-Low-Carbohydrate Diet-Related Urban Legends
Some well-meaning yet sadly misinformed nutrition "experts" have claimed that additional weight loss on very-low-carbohydrate diets is entirely due to the loss of body water. However, the classic study by Dr. Rabast and co-workers demonstrated that alterations in the water and electrolyte balance observed during the low-carbohydrate diets are reversible phenomena and should thus not be regarded as causal agents of the different weight reduction. Also, the modern studies that measured body composition by dual-energy X-ray absorptiometry did not find any indication of dehydration. So, the greater weight loss from a very-low-carb diet is largely attributable to fat loss. Old school nutrition "experts" have also proposed that a very-low-carbohydrate diet sets the stage for a significant
loss of muscle mass
as the body recruits amino acids from muscle protein to maintain blood sugar (glucose) via gluconeogenesis (formation of glucose within the body from precursors other than carbohydrates). This assumption is clearly fallacious. It is true that animals share the metabolic deficiency of the total (or almost total) inability to convert fatty acids to glucose, so the primary source for a substrate for gluconeogenesis is amino acid. However, when the rate of mobilization of fatty acids from fat tissue is accelerated, as, for example, during a very-low-carbohydrate diet, the liver produces ketone bodies. The liver cannot utilize ketone bodies and thus, they flow from the liver to extra-hepatic tissues (e.g., brain, muscle) for use as a fuel. Simply stated, ketone body metabolism by the brain displaces glucose utilization and thus spares muscle mass. In other words,
the brain derives energy from stored fat during a very-low-carbohydrate diet
. Also, if the muscle is plentifully supplied with other substrates for burning (such as fatty acids and ketone bodies, in this case), then the burning of muscle protein-derived amino acids is suppressed.
is a harmless physiological state caused by regulated and controlled production of ketone bodies. Unfortunately, many health care professionals have confused dietary ketosis with
. All diabetic patients know that the detection in their urine of the ketone bodies is a danger signal that their diabetes is poorly controlled. Indeed, in severely uncontrolled diabetes, if the ketone bodies are produced in massive supranormal quantities, they are associated with ketoacidosis . In this life-threatening complication of
, ketone bodies are produced rapidly, which overwhelm the body's acid-base buffering system. However, very-low-carbohydrate diet cannot lead to dangerous ketoacidosis in healthy subjects, because ketone bodies have effects on insulin and glucogen secretions that contribute to the control of the rate of their own formation.
A Brief Review of Studies
A number of scientific studies have demonstrated that a very-low-carbohydrate diet promotes fat loss while maintaining or even increasing muscle mass. For example, Dr. Young and co-workers compared three diets containing the same amounts of calories (1,800 kcal/day) and protein (115 grams/day) but differing in carbohydrate content (
American Journal of Clinical Nutrition
. 1971 Mar;24(3):290-6). After nine weeks on the 30-g, 60-g and 104-g carbohydrate diets, weight loss was 16.2, 12.8 and 11.9 kg and fat accounted for 95, 84, and 75% of the weight loss, respectively. So, the authors concluded, "Weight loss, fat loss, and percent of weight loss as fat appeared to be inversely related to the level of carbohydrate in the isocaloric, isoprotein diets." In laymen's terms,
the more carbs these test subjects consumed, the less fat they lost.
Dr. Jeff Volek and colleagues investigated the effects of a six-week very-low-carbohydrate diet on body composition in healthy normal-weight men (Metabolism. 2002 Jul;51(7):864-70). Twelve subjects switched from their habitual diet (48% carbohydrates) to a very-low-carbohydrate diet (8% carbohydrates) for six weeks and eight men served as controls, consuming their normal diet. Although subjects were encouraged to consume adequate dietary energy to maintain body mass during the intervention, the results revealed that
fat mass was significantly decreased
(-3.4 kg) and lean body mass significantly increased (+1.1 kg) at week six (as measured by DEXA). There were no significant changes in composition in the control group. The authors concluded that a very-low-carbohydrate diet resulted in a significant reduction in fat mass and an accompanying
increase in lean body mass
in normal-weight men. In other words, the entire loss in bodyweight was from body fat. Another well-controlled study by Dr. Volek and co-workers compared effects of isocaloric, energy-restricted very-low-carbohydrate diet and low-fat/high-carbohydrate diets on
and body composition in overweight/obese men and women (Nutrition & Metabolism. 2004 Nov 8;1(1):13). Despite significantly greater calorie intake (1855 versus 1562 kcal/day), a group comparison revealed a distinct advantage of a very-low-carbohydrate diet over a
for weight loss/fat loss for men. In fact, 5 men showed more than 10 pounds difference in weight loss. The majority of women also responded more favorably to the
, especially in terms of trunk fat loss. Furthermore, the individual responses revealed that three men and four women who did the very-low-carbohydrate diet first, regained body mass and fat mass after the switch to the low-fat, whereas no subjects regained weight or fat mass after switching to the ketogenic diet. To review all the related studies, read my recent scientific papers published in J
ournal of the International Society of Sports Nutrition
Nutrition & Metabolism
(http://www.nutritionandmetabolism.com/content/3/1/9). Once you have read them, you will also conclude that, when it come to fat loss, a calorie is certainly NOT a calorie. In fact, some studies suggest that calorie content may not be as predictive of fat loss as is reduced carbohydrate consumption.
The Ultimate Nutritional Program for Short-Term Fat Loss
This program is targeted to those who wish to MAXIMIZE short-term fat loss while maintaining or increasing muscle mass.
1.) Follow a very-low-carbohydrate, high-protein, moderate-fat diet. The most important point is to
keep carbohydrate intake very low. Also, make sure you
take in adequate amounts of protein with every meal. You hardly need to limit fat intake during a very-low-carbohydrate diet. Choose only low-glycemic, high-fiber carbohydrate sources (vegetables, legumes, etc.). However, immediately after resistance exercise you can take in a small amount high-glycemic carbohydrates with a fair amount of high quality protein (e.g.,
CFM whey isolate). Good protein sources include fish (
healthy fats!), eggs, lean meats, and carbohydrate-free
protein powders such as
NytroWhey, which is all
CFM whey isolate protein.
2.) Critical supplements are
multivitamin-mineral complexs (e.g.,
Super MegaMax), pure
creatine powder or a carbohydrate-free creatine transport formula, and a well-designed
fat loss-enhancing supplement (e.g., Tetrazene ES-50). Also suggested are
BCAA's to stimulate protein synthesis, and to help maintain high protein intake without carbs, use the
NytroWhey. 3.)Remember to drink a lot of water and other calorie-free fluids. Also, make sure you take in adequate amounts of potassium and sodium.If you decide to give this program a try, you may need to modify your
resistance-training program. For example, it's a good idea to focus on heavier weights for fewer reps (three to eight), because the energy is primarily derived from phosphocreatine stores.
Phosphocreatine serves as the cell's energy reservoir to provide rapid phosphate-bond energy to resynthesize ATP, a high-energy molecule serving as the ubiquitous energy currency of cells. This is a more rapid pathway than ATP regeneration in glycogen breakdown (glycogenolysis). Thus, phosphocreatine becomes important in maximum efforts lasting up to 10 seconds. Ingesting
creatine monohydrate (
German creatine) at the dosage of 20 to 30 grams per day for two weeks increases intramuscular concentrations of free creatine and phosphocreatine by up to 30 percent. Consequently, creatine is a very useful supplement in the very-low-carbohydrate diet. This program is not for endurance athletes. Consult with your physician before starting this program if you have any medical condition or if you are taking any medication. Do not follow this program if you are pregnant or nursing.
Lifelong Health and Weight Control Although a very-low-carbohydrate diet is a very effective short-term approach to fat loss, a moderate-carbohydrate diet is probably the most effective diet for lifelong health and weight control. Just make sure you stick with "good carbs", i.e., vegetables, fruits, legumes, oatmeal and other unprocessed whole grains. Moderate-carbohydrate diets are also better for those who wish to maximize gains in muscle mass. But when it comes to short-term fat loss, while maintaining and even gaining muscle, your best dietary approach is the proven and powerful very-low-carbohydrate diet. Questions or comments? Visit the
ProSource Fitness Forum.
Anssi Manninen, M.H.S., is a well-published research scientist in the sports nutrition field. He holds an M.H.S. in sports medicine from the University of Kuopio Medical School. His current position is Senior Science Editor at Advanced Research Press, a publisher of Muscular Development, FitnessRx for Men, and FitnessRx for Women. Anssi is also an Associate Editor for Nutrition & Metabolism www.nutritionandmetabolism.com, a leading scientific journal in the area of nutritional biochemistry.