Nutritional Pearl: Should You Eat Breakfast?
Joe is a 40-year-old obese man with prediabetes who is struggling to lose weight. At his most recent checkup, he tells you that he rarely eats breakfast and instead has a large lunch and dinner. He asks if this could be affecting his weight-loss efforts.
How do you advise your patient?
What is the correct answer?
(Answer and discussion on next page)
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Answer: Breakfast improves insulin sensitivity, which could in turn help with weight-loss efforts.
Research has shown that those who eat breakfast tend to eat more regularly throughout the day, and when they snack, they tend to choose healthier snacks. Those who eat breakfast are also less likely to overindulge at lunch or dinner, making it practically dogma that trying to lose weight requires eating breakfast.
It appears that we may need to rethink that.
The study I'm sharing with you today was carried out as part of a larger study called the Bath Breakfast Project. As you might guess from the name, the study compares the effects of eating breakfast or skipping breakfast "on energy balance and human health." This is a truly impressive study: in addition to the usual body and weight measurements (ie, waist circumference, height), the authors also determined the participants' resting metabolic rate (through analysis of oxygen/carbon monoxide exchange in the breath), measured their actual body fat using X-ray absorptiometry, took tissue samples from abdominal fat, and performed blood tests not just for cholesterol scores and glucose levels, but also for circulating hormones. The participants were further subjected to an oral glucose tolerance test—and all of this was repeated at the end of the 6-week study.
All of the participants in this portion of the Breakfast Project were clinically obese, as defined not by body mass index but by the amount of body fat as compared to the amount of lean muscle and bone in their body. These 23 men and women, who were otherwise metabolically healthy, were randomly assigned to a breakfast group or a fasting group; the breakfast group was instructed to eat at least 700 calories before 11 o'clock in the morning, with at least half of those calories to be consumed within 2 hours of waking up. The fasting group was instructed to consume nothing other than plain water before noon. Before the study started, the authors carefully trained the participants to weigh and record everything they ate, and further instructed them to keep all of the packaging for any prepackaged foods they ate for the 6 weeks of the study.
Their results are quite interesting: since the participants wore accelerometers constantly throughout the study, the authors could tell that those who ate breakfast were more active early in the day than those who did not eat breakfast, and those who ate breakfast also showed better insulin sensitivity in the glucose tolerance test. That's the entirety of the difference between the groups, however. Both groups tended to consume about the same number of calories overall, with the breakfast eaters consuming slightly more. Neither group's basal metabolic rates changed significantly, nor did their body mass index or waist circumference, while both groups' total and LDL cholesterol scores went up about the same small amount.
What’s the Take-Home?
The real takeaway here is the better insulin sensitivity in breakfast eaters. It's important for those at a clinically normal weight, but in those who are already obese, and therefore at statistically higher risk of diabetes and the health issues that often come with it, better insulin sensitivity means better control of blood sugars, less risk of prediabetes and diabetes, and decreased inflammation. It can't be seen in a short-term study like this one, but better control of blood sugars could also help with weight management over the longer term. Eat your breakfast for long-term health reasons, not just because you are or are not working on your weight.
1. Chowdhury EA, Richardson JD, Holman GD, Tsintzas K, Thompson D, Betts JA. The causal role of breakfast in energy balance and health: a randomized controlled trial in obese adults. Am J Clin Nutr. 2016;103(3):747-756.