Maybe you’re diligent about tracking your food and working on hitting your weight goals by creating a modest caloric deficit, but you’ve hit a plateau along the way. You might even be going in the other direction, and gaining weight despite feeling motivated and disciplined.
In either case, one of the factors to consider is not just what you eat, but when.
Meal timing is a strategy that’s often considered for improving weight loss and boosting athletic performance, and that’s because it has an effect on circadian rhythms.
Quick physiology refresher: Every living being, from humans to bacteria, has a cycle that’s about 24 hours, and this cycle helps determine sleep and eating patterns, among many other functions. Hormone release, hunger signals, digestion, cell regeneration, sleepiness, waking up, body temperature — all of these are affected by how these rhythms work.
It isn’t just your general circadian rhythm that’s at play here — your digestive system has its own circadian cycle. When this gets thrown off, you may be subject to effects like weight gain, digestive upset and cravings for high-calorie foods.
Some research suggests tweaking meal timing — particularly eating an early dinner and refraining from eating again until morning — may help keep your circadian rhythm going strong. In one study, participants who had the majority of their calories before 3 p.m. saw improvements in insulin sensitivity, blood pressure and oxidative stress.
In another study, women with metabolic syndrome were asked to follow a 1,400-calorie diet, with one group eating most of those calories at breakfast and lunch, and the other group having at least half of that caloric intake at dinner. After three months, the first group’s participants lost an average of 19 pounds, and the second group only about 8 pounds each — despite everyone eating the exact same number of calories.
Research is ongoing about meal timing and circadian rhythm, but it may be helpful to consider changing your meal times to see what kind of effect that might have for you, suggests Emily Tills, RDN, of Nourished with Emily.
Most of all, establishing consistency in terms of an eating schedule can be important for clicking with your own circadian rhythm, she says. Combining that with a regular sleep schedule can have an even more powerful effect.
“It’s not true that everything you eat after 7 p.m. turns into fat, but the timing of meals, as well as sleep, can have an effect,” says Tills. “Our bodies like routine, so if we can start to make a more rigid eating schedule, and stick to it seven days a week, we may be able to see better results.”
Meal timing alone won’t cause you to lose or gain weight, or dramatically increase muscle mass, unless you make changes to your diet, Tills emphasizes.
Simply changing when you eat — for example, having the majority of calories earlier in the day, or maybe trying intermittent fasting as well — will have limited effect if you’re skimping on nutritious foods, she says.
But it should be considered for adding to your collection of healthy lifestyle habits, like lowering stress, staying moderate with alcohol and increasing exercise.
Just as you track your food, jotting down when you eat and the effect it has in other ways — like energy levels, sleep and mood — can be useful for seeing how your habits affect each other, advises registered dietitian Kristen Smith, a spokesperson for the Academy of Nutrition and Dietetics.
“A disruption in following one’s typical circadian rhythm has been associated with a higher calorie consumption throughout the day, and potential negative effects for metabolic health,” she says. “While it may be initially challenging to achieve, maintaining a consistent schedule is helpful to create and set a circadian rhythm that benefits your health.”
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