When do we eat?

For weight loss, it’s all in the timing.

When we’re trying to lose weight, we tend to focus on the what and the how. As in what should we eat and how should we adjust our behavior. After all, nothing has proven to be more effective than a healthy combination of diet and exercise. But it means that we tend to overlook the when of our diets. And for many of our body’s most important functions, timing is everything.

Nearly every organism on the planet lives their lives on a 24-hour cycle of waking and sleeping. This is what’s known as the circadian rhythm — it governs our metabolism, restores our energy, and structures our days. Doctors have known about the connections between our circadian rhythm and our health for centuries, and its effects on weight loss have long been a focus of study.

The conventional wisdom is that we shouldn’t eat right before going to bed if we want to lose weight. We can’t burn those calories in our sleep, right? Well, yes and no. It turns out that an early dinner can be a very good thing, but not necessarily for the reasons you might think.

Last year, scientists found that by aligning mealtimes with your circadian rhythm, your metabolism doesn’t burn more calories — but it does reduce appetite and burn more fat. People who ate breakfast at 8 a.m. and dinner at 2 p.m. produced less ghrelin, the hormone that causes hunger, and had higher rates of fat-burning than people who ate breakfast at 8 a.m. and dinner at 8 p.m. In other words, eating when we’re most active rather than when our bodies are winding down.

The longer period of fasting (18 hours versus 12) seems to have a noticeable impact. Not only was hunger reduced, but hunger pangs were more reliable, evenly spread out and easily anticipated. The fat-loss seems to come from increased oxidation, which is also tied to our metabolism. More study into the science behind this is necessary, but what it tells us so far is quite valuable.

This practice of Early Time-Restricted Feeding (ETRF), a type of Intermittent Fasting, could be a useful tool for people working to lose weight as well as their physicians. Anyone who’s struggled with obesity knows that appetite is a major challenge to sustainable change. Controlling or suppressing appetite without the use of medication or surgery can be a major supplement to the rest of your regimen.

Of course, it’s not easy to just move your dinnertime ahead by six hours. We tend to schedule our lives to match the people around us, and it’s hard to tell the rest of the family to get ready for dinner at 1:30 in the afternoon. But the principle of ETRF is still handy, and it can be adjusted to fit your lives. With the unconventional schedules that COVID-19 has introduced for so many of us, now could be a good time to give it a try.

If you are struggling to lose weight effectively, have a conversation with your doctor about developing a mealtime schedule that puts your circadian rhythm to work.