Abstract
BackgroundObesity is becoming more prevalent in older people. A management strategy in obese, young adults is to increase dietary protein relative to other macronutrients. It is not clear if this is effective in obese, older individuals. Obesity may be associated with diminished sensitivity to nutrients. We have reported that a 30-g whey protein drink slows gastric emptying more, and suppresses energy intake less, in older, than younger, non-obese men. The aim of this study was to determine the effect of a 30 g whey protein drink on energy intake, GE and glycaemia in obese, older and younger men.MethodsIn randomized, double-blind order, 10 younger (age: 27 ± 2 years; BMI: 36 ± 2 kg/m²), and 10 older (72 ± 1 years; 33 ± 1 kg/m²), obese men were studied twice. After an overnight fast, subjects ingested a test drink containing 30 g whey protein (120 kcal) or control (2 kcal). Postprandial gastric emptying (antral area, 2D Ultrasound) and blood glucose concentrations were measured for 180 min. At t = 180 min subjects were given a buffet meal and ad libitum energy intake was assessed.ResultsOlder subjects ate non-significantly less (~20%) that the younger subjects (effect of age, P = 0.16). Whey protein had no effect on subsequent energy intake (kcal) compared to control in either the younger (decrease 3 ± 8%) or older (decrease 2 ± 8%) obese men (age effect P > 0.05, protein effect P = 0.46, age × protein interaction effect P = 0.84). Whey protein slowed gastric emptying, to a similar degree in both age groups (50% emptying time: control vs. protein young men: 255 ± 5 min vs. 40 ± 7 min; older men: 16 ± 5 min vs. 50 ± 8 min; protein effect P = 0.001, age effect P = 0.93, age × protein interaction effect P = 0.13).ConclusionsOur data suggest that obesity may blunt/abolish the age-related effect of whey protein on suppression of energy intake.
Highlights
The BMI range associated with lowest morbidity and mortality increases with age[6], a BMI higher than 30 kg/m2 in older people is still associated with adverse health outcomes, including diabetes, hypertension and heart disease
We have reported that the acute suppression of energy intake by whey protein, administered either intraduodenally[17], or orally[33], is less in healthy, non-obese, older than younger men, suggesting that the use of protein supplements to promote weight loss may not be as affective in older as younger adults[33]
Gastric emptying In one older subject the quality of antral images was insufficient to determine gastric emptying on both days, so data for this subject were excluded from analysis
Summary
While the number of older people is increasing worldwide[1,2], it is not as well appreciated that obesity rates are the BMI range associated with lowest morbidity and mortality increases with age[6], a BMI higher than 30 kg/m2 in older people is still associated with adverse health outcomes, including diabetes, hypertension and heart disease. Insufficient protein intake in obese older individuals exacerbates muscle loss[19]. This muscle loss, which may lead to sarcopaenia, is associated with functional impairment, increased rates of falls, increased nursing home admissions, and other adverse outcomes[10,20,21,22,23,24,25,26]. A management strategy in obese, young adults is to increase dietary protein relative to other macronutrients. It is not clear if this is effective in obese, older individuals. The aim of this study was to determine the effect of a 30 g whey protein drink on energy intake, GE and glycaemia in obese, older and younger men
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