I have seen several different sources of nutrition information recently “debunking” nutrition myths. One of the myths being debunked relates to the number or frequency of meals each day and the associated health impacts.
Typically the premise being “debunked” is that more frequent, smaller meals each day is associated with increased weight loss or increased metabolism.
This premise is associated with the fact that one component of metabolism is the thermal effect of food, i.e. metabolism increases when we eat due to digestive processes. There is, however, no scientific evidence that metabolism is increased by eating more frequently. In fact, more than half of our metabolism is attributed to basal metabolism, which is the rate at which you burn calories when at rest (i.e. not exercising or eating).
But just because the practice of eating smaller meals more frequently doesn’t cause more calories to be burned does not mean that the practice should be abandoned. There are legitimate situations where this practice is recommended. Eating more frequently helps manage blood sugar levels, avoiding spikes and falls, which can lead to cravings and overeating. This practice is frequently recommended for persons with a metabolic disorder such as diabetes or hypoglycemia. Metabolic benefits of increased meal frequency may include lower total cholesterol levels, more cholesterol synthesis, lower insulin and blood glucose levels, and increased bile acid losses due to more frequent bile acid cycling. More frequent, smaller meals may decrease the risk of GERD and have also been found to be helpful for patients with gastroparesis. This practice is also recommended for inflammatory bowel disorders such as Crohn’s and ulcerative colitis. Increasing the frequency of meals and reducing their size spreads nutrient load over time and prolongs the time spent in absorptive state, which is helpful for many persons with a compromised GI system.
When I tracked the references cited in support of debunking this myth, most were focused on the association with weight loss rather than promoting health or supporting any particular health issues. This is a recurrent problem with much of the nutrition reporting … we focus on counting calories and pounds rather than focusing on improvements in diet that will lead to improved health (oh, and also probably to achieving and maintaining a more healthy weight). Many of the studies cited failed to differentiate between the quality of the meals and snacks. When the meals or snacks are high in (bad) fat, high in added sugar, and/or highly processed … it is no wonder that an increase in eating frequency translates to an increase in cancer risk!
One of the assertions linking increased eating frequency to increased risk of colon cancer did catch my attention. This was the suggestion that increased exposure to high concentrations of secondary bile acids through eating more frequently may cause the increased cancer risk. An article in World Journal of Surgical Oncology in 2014 expanded the study of this theory and identified several factors that may have an effect. One factor related to the dietary quality and quantity of fat. A diet high in saturated fat elevates the levels of secondary bile acids and presents more risk while diets high in plants and fiber reflect the opposite. Other dietary factors that play a role include adequate levels of calcium and vitamin D. A second factor is that the proper synthesis of bile acids relies on many enzymes and cellular processes. These can be affected by enzyme dysfunction that occurs as we age or in the presence of some type of GI disorder. The authors noted that only a small percentage of bile acid should enter the colon and it is typically metabolized by bacterial flora. But an increased number of the population have compromised GI function that reduces the good bacteria responsible for this activity so a lack of good bacteria is another related factor. And, as is the case for almost all of our metabolic processes, the pathways for metabolism of bile acids are genetically linked and controlled. Ongoing studies are needed to identify specific genes and environmental factors, such as diet, that may be involved.
It seems that the current evidence doesn’t point to or support a specific recommendation for meal frequency. And many people can benefit from eating smaller meals more frequently. So to reduce any possibility for increased colon cancer risk, we should follow a few nutrition practices to make meals and snacks as healthy as possible: increase plant-based foods, decrease processed foods, consume good fats, support healthy intestinal bacteria, and identify and address any digestive dysfunctions through appropriate diet, herbal, and supplement support.