Juoppo sanoi:
Lukaisimpas tässä salilla laadukasta fitnessjulkaisua (nimeä en muista), jossa parin sivun artikkelissa kerrottiin että vähähiilihydraattinen dieetti polttaa
lihakset pois eikä se näinollen sovi punttaajille / urheilijoille.
Lyhyt pätkä tulevasta MD-artikkelistani:
"In general, strength-power athletes substantially decrease carb intake during cutting phase. The hormonal changes associated with a very-low-carb diet include a reduction in the circulating levels of insulin along with increased levels of glucagon. Insulin has many actions, the most well known is stimulation of glucose and amino acid uptake from the blood to various tissues. This is coupled with stimulation of anabolic processes (or synthetic reactions) such as protein, glycogen, and lipid synthesis (Glycogen refers to storage form of carbs in human body). Glucagon has opposing effects, causing release of glucose from glycogen and stimulation of gluconeogenesis and fat mobilization. So, the net stimulus would seem to be for increasing muscle protein breakdown. However, the well-controlled studies indicate that a very-low-carb diet results in body composition changes that favor loss of fat mass and preservation (or even increase) in lean body mass.
In 1971, Dr. CM Young and colleagues compared 3 diets containing same amounts of calories (1,800 kcal/day) and protein (115 grams/day) but differing in carb content (30, 60, and 104 grams). After 9 weeks of on the 30-grams, 60-grams, and 104-grams carb diets, weight loss was 16.2, 12.8, and 11.9 kilograms and fat accounted for 95%, 84%, and 75% of the weight loss, respectively. Although these results should be interpreted cautiously given the low number of subjects, we must conclude that the very-low carb group (30 grams/day) burned fat like there’s no tomorrow while maintaining muscle mass. This study was published in the well-respected America Journal of Clinical Nutrition but was ignored by the high-carb-is-the-only-way-to-go camp.
More recently, Dr. Jeff Volek and his co-workers at the University of Connecticut examined the effects of 6-week very-low-carb diet on total and regional body composition and the relationships with fasting hormones. Twelve healthy normal-weight men switched from their habitual diet (48% carb) to a very-low-carb-diet (8% carbohydrate) for 6 weeks and 8 men served as controls, consuming their normal diet. Subjects were encouraged to consume adequate dietary energy to maintain body mass during intervention.
The results indicated that fat mass was significantly decreased (-3.4 kg) and lean body mass significantly increased (+1.1 kg) at week 6. However, there were no significant changes in composition in the control group. So, Dr. Volek concluded that a very-low-carb diet resulted in a significant reduction in fat mass and a concomitant increase in lean body mass in normal-weight men. In other words, the entire loss in body weight was from lard.
Not surprisingly, results also indicated that the very-low-carb diet led to a significant decrease in insulin, and that there was a significant correlation between the decrease in insulin and the decrease in body fat. Finally, there were no adverse responses in any of the biochemical variables studied. This well-controlled study was published in the prestigious scientific journal called Metabolism, but the mainstream nutrition experts largely ignored it (“What the heck is this Metabolism anyway? I only read the Journal of the American Dietetic Association”).
Finally, Dr. KA Mecklin and colleagues at University of Guelph examined the effects of a very low-carb diet on weight loss and biochemical parameters in overweight women. Twenty women completed an 8-week trial that reduced their daily carb intake from 232 to 71 grams. The average weight loss was 5 kilograms, with a loss of 3.4% body fat (4 kilograms), and a loss of 1 kilogram of lean body mass (mostly water). Furthermore, the systolic blood pressure decreased by an average of 9.0 mmHg and the diastolic blood pressure decreased by 7 mmHg. Also, total cholesterol decreased significantly, all of which was accounted for by a decrease in LDL cholesterol (“bad cholesterol”) with no change in HDL cholesterol (“good cholesterol”). Finally, triacylglycerols (harmful blood lipids) decreased significantly. So, the authors concluded, “carbohydrate restriction to 70 g or less with concomitant energy restriction, without changes in protein or fat consumption, promotes weight loss, and improvements in body composition, blood pressure, and blood lipids without compromising glucose tolerance in moderately overweight women.”