Pilot study for the development of a screening questionnaire to detect sarcopenic obesity.

BACKGROUND/GOAL: Caloric restriction-the most prevalent obesity treatment-has a 97% failure rate when spread over 5-7 years. Sarcopenic obesity is thought to be the consequence of chronic dieting and the cause of weight management problems. This pilot study's goal was to develop a screening questionnaire that detects sarcopenic obesity in young and middle-aged female adults. SUBJECTS/METHOD: A total of 23 women (ages 19-59) completed a sarcopenic obesity questionnaire and were assessed for total body weight (TBWt), percent fat mass, and percent fat-free mass (%FFM) using the Bod Pod (air plethsmography), and bioelectrical impedance analysis (BIA). Appendicular skeletal mass (ASM) was calculated using BIA. Resting energy expenditure was determined using indirect calorimetry, and the basal metabolic rate (BMR) was calculated using BIA. RESULTS: The screening questionnaire score was negatively correlated with BMR (r2 = 0.885), %FFM (r2 = 0.86), ASM (r2 = 0.79) relative to TBWt and to ASM/BMI (r2 = 0.58). The screening questionnaire had an acceptable sensitivity (83%) and specificity (87%) in detecting sarcopenia measured using ASM/BMI. CONCLUSION: This pilot intimates that subjects who frequently dieted suffered from a disproportionally lower FFM and BMR relative to the TBWt. The questionnaire can help clinicians recognize the presence of sarcopenic obesity in patients.

Feeding a low energy diet and refeeding a control diet affect glycolysis differently in the slow- and fast-twitch muscles of adult male Wistar rats.

Muscle glycogen concentrations in underfed (HYPO) and refed rats (RE) in an earlier study did not correlate with fatigue. We hypothesized that underfeeding slowed glycolysis in the slow-twitch soleus, but not in the fast-twitch extensor digitorum longus (EDL). Thirty adult male Wistar rats were randomly assigned to receive one of two isovolemic and micronutrient-complete liquid diets, a control (CN) energy-complete diet for 10 d or a diet 80% lower in energy (HYPO) for 7 d producing a 20% loss of initial weight. Rats were refed an energy-complete diet for 1 or 4 d (RE1, RE4). Rats were then anesthetized, and the soleus and EDL muscles of the hindlimbs were isolated and electrically stimulated in situ. The pre- and postfatigued muscles were freeze-clamped, lyophilized and stored at -70 degreesC until assayed for specific glycolytic and Krebs cycle metabolites. The HYPO diet caused significantly slower glycolysis in the stimulated soleus but not the EDL compared with the CN diet as supported by the following: 1) a lower fructose-1,6-bisphosphate (F-1,6-P2)/fructose-6-phosphate (F-6-P) ratio; 2) a greater glucose-6-phosphate (G-6-P)/lactate ratio; 3) a lower lactate/glycogen ratio; and 4) lower lactate concentration. Four days of refeeding normalized the F-1,6-P2/F-6-P ratio, but did not improve the lactate/glycogen or the G-6-P/lactate ratios. We conclude that undernutrition compromises glycolysis only in slow-twitch muscles and that 4 d of refeeding restores phosphofructokinase activity.

Effect of hypoenergetic feeding and high-carbohydrate refeeding on muscle tetanic tension, relaxation rate, and fatigue in slow- and fast-twitch muscles in rats.

Studies using nuclear magnetic resonance have shown that undernutrition affects muscle performance and energetics. It is unclear to what extent underfeeding and refeeding influence the availability of muscle glycogen, net glycogenolysis, skeletal muscle wasting, and recovery. We hypothesized that muscle performance is independent of muscle size and weight, is specific to muscle type, and is unrelated to muscle glycogen concentrations. Slow- and fast-twitch muscles were studied in three groups of adult male Wistar rats: well-fed controls, hypoenergetically fed (Hypo) rats, and rats refed for 4 d after the hypoenergetic diet. Glycogen concentrations and net glycogenolysis; serum glucose, insulin, and protein concentrations; and muscle weight, protein, and cross-sectional area were studied relative to the performance of both types of muscles. Our study controlled for muscle size, weight, and type and electrolyte-micronutrient deficiency. Undernutrition affected muscle performance in five ways. First, compared with controls, fatigue increased only in the soleus muscles of Hypo rats yet the maximal relaxation rate (MRR) decreased in both the soleus and extensor digitorum longus (EDL) muscles. Second, muscle glycogen concentrations did not significantly correlate with fatigue in either the soleus or the EDL although net glycogenolysis was significantly correlated with fatigue in the soleus (r = -0.64; P > 0.01 < 0.05). Third, lower glycogen concentrations did not hinder net glycogenolysis in the EDL of Hypo rats or the soleus of refed rats. Fourth, muscle weight, size, and protein were dissociated from function. Fifth, refeeding did not restore muscle endurance; however, the MRR of the soleus normalized. In conclusion, glycogen values and muscle performance did not correlate but net glycogenolysis correlated with fatigue in the soleus. Also, there was a dissociation between muscle weight, size, and protein and muscle function during hypoenergetic feeding and refeeding.