“Don’t eat after 7 p.m.,” “Close the kitchen after dinner.” This advice is so frequently repeated (typically directed at people who are trying to lose weight or avoid gaining weight) that it’s taken on a veneer of truth and common sense.

Even among my patients who have put the pursuit of weight loss behind them (or are working on it), the idea of avoiding evening or night eating is often so ingrained that they won’t eat at that time even if there are good reasons to:

• They’re a healthcare provider in a hospital (where it’s generally hard to find a time and permitted space to eat) and they don’t get off shift until past 7 p.m.
• They have a food allergy or serious food intolerance (celiac disease, lactose intolerance) and went to someone’s house for dinner only to find there was little they could eat.
• They’re having trouble eating enough, and evening is a time when they feel more able to eat.

But back to the original “rule”: is it true that eating at night causes weight gain?

You are not a mouse

More than a decade ago, a study did find that eating at night lead to significant weight gain, compared with eating during the day — but that study was on mice, and you are not a mouse. Research on humans is a little more nuanced.

For example, a 2023 study randomly assigned 16 people with a body mass index (BMI) in the “overweight” or “obese” range to either eat their meals earlier in the day (8 a.m., noon and 4 p.m.) or later in the day (noon, 4 p.m. and 8 p.m.) during a six-day laboratory stay.

Several weeks later they returned to the lab to eat the same number of calories, but on the opposite schedule. The researchers discovered that when participants ate later in the day, they tended to feel hungrier and have lower levels of leptin — a hormone that makes you feel full. They also burned fewer calories during the day. Yes, together, this could lead to weight gain.

The role of circadian rhythms

Now, there are some good reasons to limit or avoid eating at night. For example, eating too close to bedtime can cause heartburn or acid reflux. Also evolving research strongly suggests that eating at the “wrong” time of day causes a misalignment in our circadian rhythms, or internal clocks, that can increase our risk of, yes, weight gain, but more concerningly cardiovascular disease, diabetes and other health conditions. Our bodies are designed to eat and be active during the day and fast and rest at night.

Because of this design, our bodies use calories and carbohydrates (energy!) more effectively earlier in the day, which helps support metabolic health. So, while night eating can disrupt circadian rhythms, so can skipping breakfast. And I have a lot of clients who skip breakfast, because they’re “just not hungry.”

(As I explain, they’re just not hungry because their bodies have given up on sending them hunger cues in the morning, even though their bodies do need morning fuel.)

A recent study that followed 48,150 adults without diabetes, cardiovascular disease or cancer for four years found that those who skipped breakfast and ate at night gained slightly more weight — about a pound, big woo — than those who did neither. Eating a low-quality diet made things worse, which is a reminder that while when we eat may matter, what and how much we eat matters, too.

Final food for thought

What can you do if your schedule means you have to eat dinner late? From a health standpoint, try to make that meal a smaller, lighter one that’s higher in protein than in carbohydrates, and make breakfast and lunch bigger meals.

(I know, I know, this can be a hard flex with some people’s schedules, but it’s about doing the best you can.)

If you eat dinner at a “normal” time but want to eat more than just a light snack later in the evening, explore whether you’re eating enough during the day. If you are, is your evening eating is related to stress or emotional eating? Is it due to deeply ingrained habits such as eating while watching TV?

If you often find yourself waking up multiple times to eat on more than four nights per week, talk to your doctor, because this could be a sign of night eating syndrome, an eating disorder that is often coupled with a sleep disorder.

Need more help making changes that support health and well-being by tuning into your body's wisdom rather than relying on external rules? Click here to schedule a free 20-minute Discovery Call to talk about your concerns, and if you would benefit from nutrition therapy.

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​Disclaimer: All information provided here is of a general nature and is furnished only for educational purposes. This information is not to be taken as medical or other health advice pertaining to an individual’s specific health or medical condition. You agree that the use of this information is at your own risk.

Until next time,