Effects of short-term very low-carbohydrate or conventional diet on strength performance.
Study Goal
The researchers aimed to compare the effects of a very low-carbohydrate, high-protein diet (VLCD) versus a conventional restrictive diet (CONV) on strength performance in sedentary women.
Results Summary
Both diets led to significant body mass reduction without significant differences between them. Neither diet impaired acute strength performance, as measured by knee extension isokinetic strength tests.
Population
Sedentary women
Effective Dosage
VLCD (<40 g carbohydrate); CONV (500-800 kcal restrictive, 48% carb, 22% protein, 30% fat)
Duration
1 week
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
very low-carbohydrate and high protein diet (VLCD) | decrease | body mass | Sedentary women | -2.6+/-1.0% | reduced | #1 |
low energy conventional diet (CONV) | decrease | body mass | Sedentary women | -1.9+/-1.3% | reduced | #2 |
very low-carbohydrate and high protein diet (VLCD) | no change | sum of the total work in three sets (ATW) with 90 s rest interval | Sedentary women | 4850+/-1002 J vs. 4801+/-973 J | no significant differences were detected | #3 |
very low-carbohydrate and high protein diet (VLCD) | no change | sum of the total work in three sets (ATW) with 180 s rest interval | Sedentary women | 4812+/-1174 J vs. 4812+/-1210 J | no significant differences were detected | #4 |
low energy conventional diet (CONV) | no change | sum of the total work in three sets (ATW) with 90 s rest interval | Sedentary women | 4709+/-729 J vs. 4530+/-996 J | no significant differences were detected | #5 |
low energy conventional diet (CONV) | no change | sum of the total work in three sets (ATW) with 180 s rest interval | Sedentary women | 4760+/-732 J vs. 4816+/-702 J | no significant differences were detected | #6 |
Short-term hypoenergetic diets, irrespective of the carbohydrate content | decrease | body mass | - | - | seem to reduce significantly | #7 |
Short-term hypoenergetic diets, irrespective of the carbohydrate content | no change | acute strength performance | - | - | do not impair | #8 |
AIM: Weight reduction strategies usually include diet and regular physical activity. A very low-carbohydrate and high protein diet (VLCD) may be preferred instead of a low energy conventional diet (CONV). The effects of VLCD on strength performance are yet to be understood. Aim of the study is to determine the effects of two different restrictive diets on strength performance. METHODS: Sedentary women were assigned to either a VLCD (<40 g carbohydrate; n=12) or a CONV diet (500 to 800 kcal restrictive; 48%, 22% and 30% from carbohydrate, protein and fat, respectively; n=12). Knee extension isokinetic strength tests (3 yen 15 reps at 60 degrees .s-1, with 90 or 180 s rest interval between sets) were performed prior and after a one week diet period. RESULTS: Both groups reduced body mass (VLCD: -2.6+/-1.0% vs. CONV: -1.9+/-1.3%; P<0.05), with no between diets effect. The sum of the total work in three sets (ATW) was 4850+/-1002 J vs. 4801+/-973 J with 90 s rest interval, and 4812+/-1174 J vs. 4812+/-1210 J with 180 s rest interval, respectively, in the pre vs. post-VLCD period. For CONV, values were 4709+/-729 J vs. 4530+/-996 J with 90 s rest interval, and 4760+/-732 J vs. 4816+/-702 J with 180 s rest interval, respectively, in the pre vs. post-CONV treatment. No significant differences were detected in the ATW between groups. CONCLUSION: Short-term hypoenergetic diets, irrespective of the carbohydrate content, seem to reduce significantly body mass, but do not impair acute strength performance.