When you combine a traditional weight-loss diet with strength training you lose just as much fat and retain just as much muscle mass as you would on a low-carb diet. That’s the take-home message from the human study that Brazilian sports scientists Claudia Meirelles and Paulo Gomes published in the Journal of Sports Science and Medicine.
The researchers got 21 participants whose BMI was higher than 25 to lose weight over an 8-week period. All participants had at least 3 months’ experience of strength training, and did weight training during the experiment.
12 of the participants lost weight by going on a low-carb diet. For the first four weeks of the experiment they were allowed 30 g carbohydrates daily, after which they were allowed to increase their carb intake each week by 10 g. The participants did not count calories.
The other group went on a traditional weight-loss diet and did count calories. These participants reduced their intake so that they were consuming 30 percent less energy than they were burning. The energy was derived for 15 percent from protein, 30 percent from fat and 55 percent from carbohydrates.
The low-carb group gained a kilogram of lean body mass; the lean body mass of the traditional-diet group remained stable. The differences between the groups were not statistically significant however.
The fat percentage and waist circumference decreased by similar amounts in both groups.
The researchers multiplied the weight with which the participants trained their legs, biceps and triceps by the amount of reps they were able to do, and discovered that both groups made approximately the same amount of progress throughout the course of the experiment. In the figure below the participants who followed the traditional diet appear to do a little better than the low-carb group, but the differences between the groups are not statistically significant.
“Overweight and obese individuals submitted to resistance training while undergoing a short-term hypoenergetic dietary intervention may be capable of gaining muscle strength and maintain muscle thicknesses”, the researchers summarised. “Simultaneously, the participants experienced significant reductions in body mass and body fat, regardless of their carbohydrate intake.”
“In addition to the existing literature on the numerous health benefits of carbohydrate restriction, this research supports the conclusion that, in combination with resistance training, carbohydrate restriction is a plausible method to maintain muscle mass during energy restriction programs.”
“These results may be important to alert health professionals that carbohydrate restriction may be an alternative intervention for treating these subjects, as long as there is no specific contraindication.”
Effects of Short-Term Carbohydrate Restrictive and Conventional Hypoenergetic Diets and Resistance Training on Strength Gains and Muscle Thickness
Hypoenergetic diets and resistance training (RT) have been suggested to be important components of weight loss strategy programs; however, there is little evidence as to the chronic effects of different macronutrient compositions on strength performance and muscle mass with RT. The purpose of this study was to compare the effects of carbohydrate restrictive (CRD) and conventional (CONV) diets combined with RT on strength performance and muscle thicknesses in overweight and obese participants already involved in RT programs. Twenty-one volunteers engaged in an eight-week progressive RT program three times per week were assigned to a CRD (< 30 g carbohydrate; n = 12; 30.7 ± 3.9 km·m-2) or a CONV (30% energy deficit; 55%, 15% and 30% energy from carbohydrate, protein and fat, respectively; n=9; 27.7±2.5 km·m-2). Method: At baseline and week 8, the participants underwent body composition assessment by anthropometry, measurement of muscle thickness by ultrasound, and three strength tests using isotonic equipment. Both groups had similar reductions in body mass and fat mass as well as maintenance of fat-free mass. Muscle strength increased 14 ± 6% in the CRD group (p = 0.005) and 19 ± 9% in the CONV group (p = 0.028), with no significant differences between the groups. No significant differences were detected in muscle thicknesses within or between the groups. In conclusion, hypoenergetic diets combined with RT led to significant increases in muscle strength and were capable of maintaining muscle thicknesses in the upper and lower limbs of overweight and obese participants, regardless of the carbohydrate content of the diets.