Am J Clin Nutr 2006;83:1055-61
Johnston CS, Tjonn SL, Swan PD et al.
BACKGROUND: During weight loss, fat breakdown produces acidic substances called ketones. The greater the calorie restriction, the more ketones are produced and in excess, make the blood over acidic which can be harmful. But is there any advantage to such an excessive restriction of calorie intake compared to a moderate reduction?
Scientists at the Department of Nutrition, Arizona State University, Mesa, compared weight loss and blood changes in adults adhering to a ketogenic low-carbohydrate (KLC) diet or a nonketogenic low-carbohydrate (NLC) diet.
DESIGN: Twenty adults [body mass index 34.4] were randomly assigned to the KLC (60% of energy as fat, beginning with approximately 5% of energy as carbohydrate) or NLC (30% of energy as fat; approximately 40% of energy as carbohydrate) diet. During the 6-week trial, participants were sedentary, and 24-h intakes were strictly controlled.
RESULTS: Mean weight losses (6.3 and 7.2 kg in KLC and NLC dieters respectively) and fat losses (3.4 and 5.5 kg in KLC and NLC dieters respectively) did not differ significantly by group after 6 weeks. Blood ketone levels in the KLC dieters was 3.6 times that in the NLC dieters at week 2 , and LDL (harmful) cholesterol was directly correlated with blood ketone. Inflammatory risk and perceptions of vigor were more adversely affected by the KLC than by the NLC diet.
CONCLUSIONS: KLC and NLC diets were equally effective in reducing body weight and insulin resistance, but the KLC diet was associated with several adverse metabolic and emotional effects. The use of ketogenic diets for weight loss is not warranted.
The Healthier Weight Centre group does not recommend ketogenic diets and weekly medical monitoring ensures patients do not suffer from ketoacidosis during weight loss.
