Influence of night-time protein and carbohydrate intake on appetite and cardiometabolic risk in sedentary overweight and obese women

Abstract

The present study investigated whether whey (WH) protein, casein (CAS) protein or a carbohydrate placebo (PLA) consumed 30 min before sleep could acutely alter appetite or cardiometabolic risk the following morning. A total of forty-four sedentary overweight and obese women (BMI: 25·7-54·6 kg/m 2 ) completed this stratified, randomised, double-blind, placebo-controlled study (WH: n 16, age 27·4 (SD 5·0) years; CAS: n 15, age 30·3 (SD 8·1) years; PLA: n 13, age 28·5 (SD 7·2) years). The participants came to the laboratory at baseline (visit 1) and again in the morning after night-time ingestion of either protein or PLA (visit 2). Visit 2 was conducted at least 48 h after visit 1. During visits 1 and 2, the following parameters were measured: appetite (hunger, satiety and desire to eat); resting metabolism; blood lipid and glucose levels; the levels of insulin, leptin, C-reactive protein, insulin-like growth factor-1, cortisol and adiponectin. Data were analysed using repeated-measures ANOVA. No group £ time interactions were observed for the measured variables; however, a main effect of time was observed for increased satiety (P¼ 0·03), reduced desire to eat (P¼ 0·006), and increased insulin levels (P¼ 0·004) and homeostatic model assessment of insulin resistance values (P¼ 0·01) after the consumption of either protein or PLA. The results of the present study reveal that night-time consumption of protein or carbohydrate by sedentary overweight and obese women improves their appetite measures but negatively affects insulin levels. Long-term studies are needed to evaluate the effects of chronic consumption of low-energy snacks at night on body composition and cardiometabolic risk.Key words: Night-time eating: Whey protein: Casein protein: Obesity Common perception is that energy intake should be limited before sleep as previous research has shown that satiety in response to meals (1,2) , metabolic rate and glucose tolerance (3 -5) decrease with the time of day, which may lead to overeating and negatively affect cardiometabolic health and body composition. Indeed, data from studies on shift workers (6,7) and those with night eating syndrome (8 -10) provide evidence for an increased cardiometabolic risk with night-time eating. In the absence of data from studies on shift workers and night eating syndrome, much of the data regarding nighttime eating stem from animal models (11) and epidemiological studies (1,12 -14) . There are even fewer intervention studies demonstrating a link between night-time food intake, cardiometabolic risk factors and weight regulation. Furthermore, the adverse findings from epidemiological studies have been observed in response to large mixed meals. Thus, it remains unclear whether altering food choice (i.e. consuming small nutrient-dense, low-energy, foods or single macronutrients) would alter the trend for increased cardiometabolic risk and unfavourable body composition.To our knowledge, only one recent intervention study (15) has reported significant, albeit small, decreases in...

The Effect of Casein Protein Prior to Sleep on Fat Metabolism in Obese Men

“…Based on our earlier work showing no differences in morning fat oxidation following bedtime CAS as compared to PLA ingestion in normal weight men [9], we hypothesized that CAS and PLA would yield similar changes in SCAAT lipolysis, whole-body substrate utilization (favoring fat oxidation), growth hormone, insulin and glucose in obese men. We also hypothesized that CAS prior to sleep will increase next morning REE more than PLA, as previously reported [8,9]. By measuring SCAAT lipolysis with microdialysis and whole-body fat oxidation, we examined the mechanisms by which CAS consumption before sleep may mediate changes in metabolism and body composition.…”

“…Recent work [7,8,9,10,11,12,13] suggests that low-calorie (~150 kcals), protein-rich sources may be beneficial or non-detrimental to metabolism, health, and body composition when consumed as a snack ~30 min before going to sleep acutely (one-night) [7,8,9,11,12] and when combined with exercise for a longer duration (i.e., 4–12 weeks) [10,13]. In general, protein ingestion suppresses appetite, increases energy expenditure and muscle mass, and decreases body fat [14,15,16,17,18], encouraging support for ingesting protein-rich foods before going to sleep.…”

“…This may suggest that casein before bed may not negatively impair fat metabolism relative to fasting and therefore may be appropriate to consume in close proximity to sleep. Studies in obese women have demonstrated that CAS ingestion before sleep can increase next morning satiety and, augment REE from baseline, however no differences were detected between casein and calorically-matched whey protein or carbohydrate ingestion [8]. Additionally, regardless of macronutrient type, acute elevations in insulin and insulin resistance have been observed the morning after pre-sleep caloric intake in obese women [8].…”

“…Studies in obese women have demonstrated that CAS ingestion before sleep can increase next morning satiety and, augment REE from baseline, however no differences were detected between casein and calorically-matched whey protein or carbohydrate ingestion [8]. Additionally, regardless of macronutrient type, acute elevations in insulin and insulin resistance have been observed the morning after pre-sleep caloric intake in obese women [8]. While the latter finding is not ideal for obese populations, it is important to note that a true non-nutritive placebo was absent and food intake throughout the day was not well controlled [8].…”

“…Additionally, regardless of macronutrient type, acute elevations in insulin and insulin resistance have been observed the morning after pre-sleep caloric intake in obese women [8]. While the latter finding is not ideal for obese populations, it is important to note that a true non-nutritive placebo was absent and food intake throughout the day was not well controlled [8]. It is possible that the habitual diet during the day could have confounded the effects of nighttime macronutrient ingestion on next morning insulin and, hence, deserves further attention.…”