If you consistently work through lunch and find yourself scarfing something down late in the afternoon, your schedule could be secretly damaging your journey to lose weight.
A recent study published in the American Journal of Clinical Nutrition examined the effectiveness of a weight loss program among more than 1,200 overweight and obese people in Spain.
It found that those who carried a specific genetic variation of the protein perilipin—which is essential to burning fat throughout the body—lost less weight when they ate lunch later than 3pm than those who ate lunch earlier.
Although this study focused on people with specific genetic makeups, a similar study published in the International Journal of Obesity in 2013 also found that eating lunch late was associated with less weight loss success—regardless of any gene variations.
So Why Is Your Lunch Break Sabotaging Your Weight Loss Goals?
Just like feeling sleepy is governed by our circadian rhythms, so is feeling hungry, says Dr. Marie-Pierre St-Onge, an assistant professor at Columbia University who studies the impact of lifestyle behaviours on weight control at the New York Obesity Nutrition Research Centre.
“[Metabolism] differs among individuals, and the timing of food consumption in relation to circadian rhythm may influence weight loss,” she says.
Circadian rhythms also control insulin secretion in the body, she adds.
If you’re eating at a time when your body is less sensitive to insulin, you might have a harder time mobilising fats and losing weight.
Although the timing of lunch might affect some people’s waistlines, the researchers didn’t find any differences in weight loss when they looked at the timing of breakfast or dinner.
That could be due to the fact that the study was conducted in Spain, where nearly half of the day’s calories are consumed at lunch.
In fact, people who eat a larger lunch may already have a leg up: earlier studies suggest that people who make lunch the main meal of the day lose more weight and have lower body mass indexes.
“If you look at the breakdown of food intake in the [US] population, there are fewer calories being consumed for breakfast and lunch. If you add breakfast and lunch together that would be about 40 percent of calories, and dinner and snacks make up the other 60 percent,” she says.
More research needs to be done on the impact of meal timing, she says, but if you find yourself eating healthy but still struggling to shed pounds, making lunch your main meal—and eating it before 3pm—are manageable places to start.