Saturday, January 26, 2013

Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets

Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets

Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets1,2,3

Carol S Johnston,
Sherrie L Tjonn,
Pamela D Swan,
Andrea White,
Heather Hutchins, and
Barry Sears

+ Author Affiliations

1From the Department of Nutrition, Arizona State University, Mesa, AZ (CSJ, PDS, and AW); Conscious Cuisine, Scottsdale, AZ (SLT); and Inflammation Research Foundation, Marblehead, MA (HH and BS)


Background:Low-carbohydrate diets may promote greater weight loss than does the conventional low-fat, high-carbohydrate diet.

Objective:We compared weight loss and biomarker change in adults adhering to a ketogenic low-carbohydrate (KLC) diet or a nonketogenic low-carbohydrate (NLC) diet.

Design:Twenty adults [body mass index (in kg/m2): 34.4 ± 1.0] were randomly assigned to the KLC (60% of energy as fat, beginning with ≈5% of energy as carbohydrate) or NLC (30% of energy as fat; ≈40% of energy as carbohydrate) diet. During the 6-wk trial, participants were sedentary, and 24-h intakes were strictly controlled.

Results:Mean (±SE) weight losses (6.3 ± 0.6 and 7.2 ± 0.8 kg in KLC and NLC dieters, respectively; P = 0.324) and fat losses (3.4 and 5.5 kg in KLC and NLC dieters, respectively; P = 0.111) did not differ significantly by group after 6 wk. Blood β-hydroxybutyrate in the KLC dieters was 3.6 times that in the NLC dieters at week 2 (P = 0.018), and LDL cholesterol was directly correlated with blood β-hydroxybutyrate (r = 0.297, P = 0.025). Overall, insulin sensitivity and resting energy expenditure increased and serum γ-glutamyltransferase concentrations decreased in both diet groups during the 6-wk trial (P < 0.05). However, inflammatory risk (arachidonic acid:eicosapentaenoic acid ratios in plasma phospholipids) 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. I've been reading Phinney's books on ketogenic diets for weight loss and athletic performance. Also reviewing the A to Z study in which Atkins beat out Barry Sears The Zone diet, which allows more carbs. This study seems to exonerate the Zone approach, allowing more carbs. I suspect each of us, for genetic reasons, or because of our current state of health, has different requirements or tolerances for, carbohydrate. I have also been thinking about the Lustig/Taubes combo, that perhaps glucose ain't so bad, until the fructose damages our liver and makes us insulin resistant. If so, some of us with bad IR, diabetes or heart failure may be unable to tolerate carbs well at all. The original Atkins diet had the right idea, perhaps. Drastically cut carbs to 20g a day until you lose the weight you want (or can reasonably expect) to lose, then slowly add carbs to find the level at which you start to add weight.

I also find myself finding more truth in the "calories DO count" school of thought. Insulin probably does encourage fat deposition. It definitely increases hunger. But study after study also shows that free feeding of protein and fat causes people to voluntarily eat less. If that's the beginning and end of what low carb can do, that's pretty damn good, especially if you add in the other positive health benefits. We've gone to far if we suggest unlimited amounts of fat and protein can be consumed with no weight gain. Still putting all the pieces together and learning new things about low carb, even after first doing it 15 years ago!

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