The causal role of breakfast in energy balance and health: a randomized controlled trial in lean adults

Although consumption of 3 meals/d is the most common pattern of eating in industrialized countries, a scientific rationale for this meal frequency with respect to optimal health is lacking. A diet with less meal frequency can improve the health and extend the lifespan of laboratory animals, but its effect on humans has never been tested. A pilot study was conducted to establish the effects of a reduced-meal-frequency diet on health indicators in healthy, normal-weight adults. The study was a randomized crossover design with two 8-wk treatment periods. During the treatment periods, subjects consumed all of the calories needed for weight maintenance in either 3 meals/d or 1 meal/d. Subjects who completed the study maintained their body weight within 2 kg of their initial weight throughout the 6-mo period. There were no significant effects of meal frequency on heart rate, body temperature, or most of the blood variables measured. However, when consuming 1 meal/d, subjects had a significant increase in hunger; a significant modification of body composition, including reductions in fat mass; significant increases in blood pressure and in total, LDL-, and HDL-cholesterol concentrations; and a significant decrease in concentrations of cortisol. Normal-weight subjects are able to comply with a 1 meal/d diet. When meal frequency is decreased without a reduction in overall calorie intake, modest changes occur in body composition, some cardiovascular disease risk factors, and hematologic variables. Diurnal variations may affect outcomes.

To investigate which sociodemographic factors and behaviors are associated with breakfast skipping in adolescents and adults. Five birth cohorts of adolescent twins and their parents received an extensive behavioral and medical self-report questionnaire that also assessed breakfast-eating frequency. Finland, 1991-1995. A population sample of 16-y-old girls and boys (n=5448) and their parents (n=4660). Parental breakfast eating was the statistically most significant factor associated with adolescent breakfast eating. Smoking, infrequent exercise, a low education level at 16, female sex, frequent alcohol use, behavioral disinhibition, and high body mass index (BMI) were significantly associated with adolescent breakfast skipping. In adults, smoking, infrequent exercise, low education level, male sex, higher BMI, and more frequent alcohol use were associated with breakfast skipping. In the adult sample, older individuals had breakfast more often than younger ones. Both adults and adolescents who frequently skipped breakfast were much more likely to exercise very little compared to those who skipped breakfast infrequently. Breakfast skipping was associated with low family socioeconomic status in adults and adolescent boys, but not in girls. Breakfast skipping clustered moderately with smoking, alcohol use, and sedentary lifestyle in both adults and adolescents. Breakfast skipping is associated with health-compromising behaviors in adults and adolescents. Individuals and families who skip breakfast may benefit from preventive efforts that also address risk behaviors other than eating patterns. National Institute of Alcohol Abuse and Alcoholism (AA08315), Academy of Finland (44069), European Union Fifth Framework Program (QLRT-1999-00916), Yrjö Jahnsson Foundation, and Jalmari and Rauha Ahokas Foundation.

Overall lowering of glucose is of pivotal importance in the treatment of diabetes, with proven beneficial effects on microvascular and macrovascular outcomes. Still, patients with similar glycosylated hemoglobin levels and mean glucose values can have markedly different daily glucose excursions. The role of this glucose variability in pathophysiological pathways is the subject of debate. It is strongly related to oxidative stress in in vitro, animal, and human studies in an experimental setting. However, in real-life human studies including type 1 and type 2 diabetes patients, there is neither a reproducible relation with oxidative stress nor a correlation between short-term glucose variability and retinopathy, nephropathy, or neuropathy. On the other hand, there is some evidence that long-term glycemic variability might be related to microvascular complications in type 1 and type 2 diabetes. Regarding mortality, a convincing relationship with short-term glucose variability has only been demonstrated in nondiabetic, critically ill patients. Also, glucose variability may have a role in the prediction of severe hypoglycemia. In this review, we first provide an overview of the various methods to measure glucose variability. Second, we review current literature regarding glucose variability and its relation to oxidative stress, long-term diabetic complications, and hypoglycemia. Finally, we make recommendations on whether and how to target glucose variability, concluding that at present we lack both the compelling evidence and the means to target glucose variability separately from all efforts to lower mean glucose while avoiding hypoglycemia.