Flexible vs. rigid dieting in resistance-trained individuals seeking to optimize their physiques: A randomized controlled trial

Abstract

Background

The purpose of this study was to compare a flexible vs. rigid diet on weight loss and subsequent weight regain in resistance-trained (RT) participants in a randomized, parallel group design.

Methods

Twenty-three males and females (25.6 ± 6.1 yrs; 170 ± 8.1 cm; 75.4 ± 10.3 kg) completed the 20-week intervention (consisting of a 10-week diet phase and a 10-week post-diet phase). Participants were randomized to a flexible diet (FLEX) comprised of non-specific foods or a rigid diet (RIGID) comprised of specific foods. Participants adhered to an ~20%kcal reduction during the first 10-weeks of the intervention and were instructed to eat ad libitum for the final 10-weeks. Body composition and resting metabolic rate were assessed 5 times: (baseline, 5, 10 [end of diet phase], 16, and 20 weeks).

Results

During the 10-week diet phase, both groups significantly reduced bodyweight (FLEX: baseline = 76.1 ± 8.4kg, post-diet = 73.5 ± 8.8 kg, ▲2.6 kg; RIGID: baseline = 74.9 ± 12.2 kg, post-diet = 71.9 ± 11.7 kg, ▲3.0 kg, p < 0.001); fat mass (FLEX: baseline = 14.8 ± 5.7 kg, post-diet = 12.5 ± 5.0 kg, ▲2.3 kg; RIGID: baseline = 18.1 ± 6.2 kg, post-diet = 14.9 ± 6.5 kg, ▲3.2 kg p < 0.001) and body fat% (FLEX: baseline = 19.4 ± 8.5%, post-diet = 17.0 ± 7.1%, ▲2.4%; RIGID: baseline = 24.0 ± 6.2%, post-diet = 20.7 ± 7.1%, ▲3.3%; p < 0.001). There were no significant differences between the two groups for any variable during the diet phase. During the post-diet phase, a significant diet x time interaction (p < 0.001) was observed for FFM with the FLEX group gaining a greater amount of FFM (+1.7 kg) in comparison with the RIGID group (−0.7 kg).

Conclusions

A flexible or rigid diet strategy is equally effective for weight loss during a caloric restriction diet in free-living, RT individuals. While post-diet FFM gains were greater in the FLEX group, there were no significant differences in the amount of time spent in resistance and aerobic exercise modes nor were there any significant differences in protein and total caloric intakes between the two diet groups. In the absence of a clear physiological rationale for increases in FFM, in addition to the lack of a standardized diet during the post-diet phase, we refrain from attributing the increases in FFM in the FLEX group to their diet assignment during the diet phase of the investigation. We recommend future research investigate additional physiological and psychological effects of flexible diets and weight regain in lean individuals.

A multinational observational study of clinical nutrition practice in patients undergoing major gastrointestinal surgery: The Nutrition Insights Day

BACKGROUND AND AIMS

Patients undergoing major gastrointestinal (GI) surgery, particularly those with malignancies, have a high risk for malnutrition, requiring perioperative nutritional support to reduce complications. During the Nutrition Insights Day (NID), nutritional data of this patient population were documented in seven Asian countries.

METHODS

Observational, cross-sectional study with retrospective data collection of nutritional status, calorie/protein targets/intake, and type of clinical nutrition for up to 5 days before NID.

INCLUSION CRITERIA

Adult patients following major GI surgery, pre-existing/at (high) risk for malnutrition, on enteral (EN) and/or parenteral nutrition (PN) and latest surgery within 10 days before the NID.

EXCLUSION CRITERIA

Burns, mechanical ventilation on NID, oral nutrition and/or oral nutritional supplements (ONS) on the day before the NID, and emergency procedures.

RESULTS

536 patients from 83 hospitals, mean age 58.8 ± 15.1 years, 59.1% males, were eligible. Leading diagnosis were GI diseases (48.7%) and GI cancer (45.9%). Malnutrition risk was moderate to high in 54% of patients, low in 46%. Hospital length of stay (LOS) before the NID was 9.3 ± 19.0 days, and time since last surgery 3.7 ± 2.4 days. Lowest caloric/protein deficits were observed in patients receiving EN + PN, followed by PN alone and EN alone. Type of clinical nutrition, Body Mass Index and LOS on surgical intensive care unit (SICU) and/or surgical ward were independent predictors of caloric and of protein deficit.

CONCLUSION

There is a high prevalence of postoperative nutritional deficits in Asian GI surgery patients, who are either preoperatively malnourished or at risk of malnutrition, indicating a need to improve nutritional support and education.