Short-term effect of a protein load on appetite and food intake in diseased mildly undernourished elderly people.

BACKGROUND & AIMS: Malnutrition is a risk factor for mortality and various morbidities in the elderly. A low-energy intake often prevails and therapeutic interventions include the administration of dietary supplements, sometimes rich in proteins. We have tested the hypothesis that a protein-rich supplement inhibits appetite and decreases voluntary food intake. METHODS: Twelve mildly undernourished (BMI 21.3 +/- 2.4 kg/m2) elderly (84 +/- 7.8 yr) diseased persons were each studied under 3 conditions, in which they were given in random order at breakfast, and on consecutive days: either no supplement, a 250 kcal, 20 g protein supplement or a 250 kcal, 3.5 g protein supplement. Hunger, fullness, and desire to eat sensations were monitored half-hourly from before breakfast until lunch, and hourly from lunch until dinner. Food intake was assessed by weighing food before and after meals. Total energy and macronutrient intakes were calculated over 24 h. RESULTS: Both supplements increased energy intake (+185 kcal protein supplement, +176 kcal). Protein supplementation induced a net 17 g increase in protein intake (P < or = 0.0003). Neither supplement affected spontaneous food intake at lunch, dinner, or over the 24 h. Protein supplementation significantly depressed appetite in the breakfast to lunch period. CONCLUSION: A 250 kcal, 20 g protein supplement depresses hunger without affecting food intake in elderly diseased mildly undernourished persons.

Is a failure to recognize an increase in food intake a key to understanding insulin-induced weight gain?

The present study aimed to assess the contribution of energy intake to positive energy balance and weight gain with insulin therapy. Changes in energy intake (self-report and weighed food intake), dietary behavior (auto-questionnaires), resting energy expenditure (REE) (indirect calorimetry), physical activity (accelerometry), and glucosuria were monitored over the first 6 months of insulin therapy in 46 diabetic adults. No change in REE, activity, or glucosuria could explain weight gain in the type 1 (4.1 +/- 0.6 kg, P < 0.0001) or type 2 (1.8 +/- 0.8 kg, P = 0.02) diabetic groups. An increase in energy intake provides the most likely explanation for weight gain with insulin. However, it is not being recognized because of significant underestimation of self-reported food intake, which appears to be associated with increased dietary restraint.