Eating small but frequent meals does not boost the body’s metabolism or encourage weight loss, according to new research.
The study, carried out by the University of Warwick, found that ultimately it is calorie counting that leads to healthy weight loss.
Previous studies have shown that eating a high-fat meal allows endotoxins to enter the blood stream, causing low-level inflammation in the body. This inflammation has been linked to a future risk of developing type 2 diabetes and cardiovascular diseases.
“Size or frequency of the meal doesn’t affect the calories we burn in a day”
Milan Kumar Piya
Researchers studied whether eating multiple meals would cause repeated risk of type 2 diabetes and cardiovascular disease in obese people.
They examined 24 lean and obese women, by giving them two meals or five meals on separate days. On both days the women consumed the same number of calories in a 24-hour period.
At the end of each day, researchers found that obese women accumulated significantly higher levels of endotoxins after eating five meals compared to when they only had two.
“Our studies have identified two main findings; firstly that the size or frequency of the meal doesn’t affect the calories we burn in a day, but what matters most for losing weight is counting calories.
“Secondly, by carrying more weight, more endotoxin enters the circulation to cause inflammation and eating more often will exacerbate this risk which has been linked to metabolic diseases such as type- diabetes,” said Dr Milan Kumar Piya, lead author of the study.
“By understanding how diet affects inflammatory risk and energy expenditure, we will further our understanding of how we can better target diet intervention on an individual basis.”
The research was presented today at the Society for Endocrinology annual BES conference in Liverpool.
Background: Small frequent meals are often recommended for weight loss, with supporting evidence often provided from studies in diabetes. Dietary meal content is also relevant, as high fat meals cause systemic inflammation via gut derived bacteria, endotoxin. As such, repeated meals may exacerbate this. In contrast, dietary induced thermogenesis, related to meal size, may reduce with small frequent meals.
Aim: Therefore, the aim of this study was to compare the effect of 2 versus 5 meals on metabolic endotoxaemia and 24hr (hour) energy expenditure in lean and obese women.
Methods: In a crossover study, 24 lean (age:34(mean±SD)±10years, BMI:22.9±2kg/m2) and obese (age:42±9years, BMI:36±8kg/m2) women were given 2 or 5 isocaloric high (50%) fat meals, on two separate days. On both visits, 24hr energy expenditure was measured in whole body room calorimeters and blood samples taken 2 hourly (9am to 9pm). Serum endotoxin, glucose, insulin, lipids were measured.
Results: The obese subjects had increased area under the curve (AUC) for insulin, glucose, HOMA-IR and triglyceride (TG), with decreased HDL (p<0.01), compared with lean subjects, for both meal visits. For the entire cohort, fasting endotoxin correlated with triglyceride (r=0.32, p<0.05), and AUC for endotoxin and TG correlated in the 5 meal visit (r=0.44, p<0.05), but not the 2 meal visit. In the final 9pm blood test, the endotoxin levels were significantly higher in the 5 meal visit (p=0.05), but not the 2 meal visit. Meal frequency did not affect 24hr expenditure, in either the obese group (2124±312 vs 2142±365Kcal/day) or lean group (1724±160 vs 1683±166Kcal/day).
Conclusion: Our findings suggest in metabolically healthy lean and obese subjects, increased meal frequency may pose an inflammatory risk posed by circulating endotoxin and TGs leading to peak levels at bedtime. As such, small frequent meals may not influence diet induced thermogenesis, but may increase metabolic disease risk.