Most everyone already knows that what and how much you eat matters for weight loss. But there is growing evidence that when you eat matters too. In the very first large scale study of its type, investigators sought to examine how “meal timing” affects weight loss. Specifically, researchers followed 420 overweight study subjects who were placed on a 20-week weight loss program. The study subjects were divided in two equal groups and instructed to consume equal calories, but with different timings for the main meal, in this case lunch. “Early-eaters” consumed lunch before 3 PM, and “late-eaters” consumed lunch after 3 PM. Relative to the early-eaters, the late-eaters lost significantly less weight, lost weight more slowly, and exhibited less insulin sensitivity (a risk factor for type 2 diabetes). The late eaters were also more likely to skip breakfast and consume less food at breakfast.

The researchers concluded that the timing of large meals could be an important factor in weight loss success. Based on the studies I have reviewed, I highly recommend that you strive to eat most of your calories in the earlier parts of the day and go lighter on dinner. (International Journal of Obesity. January 29, 2013)