Can you lose fat by changing meal times?


We’ve been warned about midnight snacks. Those late night meals can creep on you, and the reason they can lead to weight gain can very well be the type of foods consumed late at night – few people chop kale for a 2AM salad.

Recent research, though, suggests that what’s eaten at night doesn’t tell the whole story. Timing matters. Unlike a car, which can be fueled at any time with no effect of fuel efficiency, most animals have an inner – circadian – clock, and this inner rhythm interacts with food intake. There are enigmatic clocks inside our brain, and in every cell in our body, and those regulate not just sleep and alertness, but also hormones and metabolic pathways. They organize our bodily functions and behaviors so that we're optimized for the time of day. Even our gut microbes show circadian variation, and our gut community can get upset when day and night feeding are interrupted.

A new pilot study tests the effect of chrononutrition – the effect of circadian rhythm on nutrition – combined with the effect of intermittent fasting, which is another concept that’s gaining popularity lately.

The study, led by Jonathan Johnston, and published in the Journal of Nutritional Science, tested whether moving breakfast 90 minutes later, and dinner, 90 minutes earlier, would make a difference. In a 10-week trial, a group of overweight people was instructed to eat freely – no caloric restrictions – with just the timing of meals restricted, and this group was compared to a control group that ate normally.

Slight timing alteration reduces fat

The researchers found that the people who changed their mealtimes lost on average twice the amount of body fat compared to the control group, despite not consciously restricting their caloric intake. With mealtime changed, the participants reported less appetite and reduced their intake spontaneously.

Asked whether they could stick to such an eating window, about half of the study group said they could. Others found the narrower eating window burdensome or incompatible with family and social life.

Unintentional caloric intake reductions are good news, especially in our obesogenic environment, which pushes us towards unintentional overeating. This, however, is a small study. The researchers now plan to expand on these preliminary findings and study larger groups in more detail.

Breakfast and breaking a fast

The morning meal is called breakfast, because once upon a time it broke a fast. People used too have a long stretch of time between the evening meal and the next morning's one.

Nowadays, with so many eating opportunities, and food so widely available, our body experiences few breaks, and for late night eaters who aren’t late risers, even nighttime offers no respite.

The study of meal timing and intermittent fasting is still in its infancy, and I’m curious to see if meal timing and expanding the intermission between meals indeed prove beneficial. These methods of adjusting eating without dieting are very appealing.

What I’m pretty sure of, is that what you eat, and how much of it, matter the most. So early or late, choose foods and portions wisely.

Like some of the participants in the trial, I’d find it hard to commit to eating by a precise time regimen. I've been moving dinnertime back and forth, and starting it on the late (sometimes very late) side in order to eat as a family, and to eat it in good company – which I see as really important, for health and for happiness.

Dr. Ayala