Part 2: Meal Timing
Last week, I talked about circadian rhythms and why quality and adequate sleep is an important part of maintaining a healthy metabolism. This week, I will go into detail about the timing of meals from one of my education sessions at the Food and Nutrition Conference and Expo.
Along with having an internal clock and a normal 24 hour circadian cycle, there is also a daily rhythm in glucose tolerance. Glucose tolerance is naturally lower in the evening. This is why breakfast is the most important meal of the day. Naturally, in the morning after an overnight fast the body wants more glucose, so it can tolerate more. Shifting the natural meal timing by skipping breakfast or sleeping all day and working all night can have long-term hormonal and metabolic effects. The bottom line: circadian systems are very important to consider with meal timing.
Eating breakfast is associated with a lower BMI. A little known fact is that breakfast should be the largest meal of the day. Due to glucose tolerance levels, our first meal of the day should be the biggest and all subsequent meals should get smaller. In other words, people who eat a higher caloric breakfast and a smaller dinner had greater weight loss success, according to a 12-week study in the 2013 International Journal of Obesity.
Timing of lunch is a major predictor for weight loss success. In a similar 2013 study in the International Journal of Obesity, early eaters lost ~25% more compared to people who ate a later lunch. People who ate a later lunch were also more likely to skip breakfast, resulting in a much larger food intake at lunch.
In summary, late eating impairs glucose tolerance, so we should never skip breakfast and strive to make it the largest meal of the day. For weight loss, lunch and dinner should both be smaller than breakfast. By re-aligning our meal timing patterns with our natural circadian sleep/wake systems, we can achieve a healthier metabolism and weight.
Written by Anna Marie Oglesbee. B.S. in Nutritional Sciences from the University of Texas at Austin, ACE Certified Group Fitness Instructor, Certified Pharmacy Technician (CPhT).