Somebody asked the question of whether or not the composition of a diet matters for Calories-Out. After all, if a calorie is a calorie it shouldn’t matter if that calorie is sugar or steak.
Turns out there was a well designed study to figure out whether different diets had different effects on Energy Expenditure. Here’s the study (JAMA, June 27, 2012—Vol 307, No. 24 2627. Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance . Cara B. Ebbeling, PhD, Janis F. Swain, MS, RD, Henry A. Feldman, PhD, William W. Wong, PhD, David L. Hachey, PhD, Erica Garcia-Lago, BA, David S. Ludwig, MD, PhD).
Compared with the pre–weight-loss baseline, the decrease in REE (Resting Energy Expenditure) was greatest with the low-fat diet (mean [95% CI], –205 [–265 to –144] kcal/d), intermediate with the low–glycemic index diet (–166 [–227 to –106] kcal/d), and least with the very low-carbohydrate diet (−138 [–198 to –77] kcal/d; overall P=.03; P for trend by glycemic load=.009). The decrease in TEE showed a similar pattern (mean [95% CI], −423 [–606 to –239] kcal/d; −297 [–479 to –115] kcal/d; and −97 [–281 to 86] kcal/d, respectively; overall P=.003; P for trend by glycemic load.001).
In layman’s terms that means that your metabolism gets hurt the least with a low carbohydrate diet. Basically, the low carb diet didn’t drop the body’s energy expenditure much at all. That’s good news if you want to preserve your metabolism. Also, from the comments section of the study:
The results of our study challenge the notion that a calorie is a calorie from a metabolic perspective. During isocaloric feeding following weight loss, REE was 67 kcal/d higher with the very low carbohydrate diet compared with the low-fat diet. TEE differed by approximately 300 kcal/d between these 2 diets, an effect corresponding with the amount of energy typically expended in 1 hour of moderate-intensity physical activity.
300 calories a day is 31 lbs a year difference in weight maintenance. That’s very significant.
A study looked at the Resting Energy Expenditure to determine the effect on weight gain (N Engl J Med 1988; 318:467-472. Reduced Rate of Energy Expenditure as a Risk Factor for Body-Weight Gain. Eric Ravussin, Ph.D., Stephen Lillioja, M.B., Ch.B., William C. Knowler, M.D., DR.P.H., Laurent Christin, M.D., Daniel Freymond, M.D., William G.H. Abbott, M.B., Ch.B., Vicky Boyce, R.D., Barbara V. Howard, Ph.D., and Clifton Bogardus, M.D.). From the study:
The estimated risk of gaining more than 7.5 kg in body weight was increased fourfold in persons with a low adjusted 24-hour energy expenditure (200 kcal per day below predicted values) as compared with persons with a high 24-hour energy expenditure (200 kcal per day above predicted values; P<0.01). In another 126 subjects, the adjusted metabolic rate at rest at the initial visit was also found to predict the gain in body weight over a four-year follow-up period.