Not hungry?
Can you skip the meal?

The full narration of the video.

Noon hits, and your stomach growls right on time. But you had a bun at ten. Is that hunger really telling you you're out of fuel? Flip it around: sometimes you're busy all day. Only at night do you realize you never ate, yet you're not hungry at all. So if you're not hungry, can you just skip it? Let's look at an experiment. Researchers asked six healthy people to eat nothing for a full day, and drew their blood every twenty minutes.

They were watching one signal: a little messenger your gut releases into the blood, whose job is to tell your brain it's time to eat. It's called ghrelin, the hunger hormone. You might expect that the longer you go without food, the more messengers get sent, climbing all the way up. It didn't. Around their usual breakfast, lunch and dinner times, it rose for a while; and with no food, it fell back down on its own.

So hunger is, in large part, an alarm clock. Your body remembers when you usually eat and rings the bell on schedule. Even if you ate two hours ago, it rings anyway. So what about the real fuel tank? Your body keeps quite a lot in reserve. The sugar stored in your liver lasts about a day; your body fat, several weeks. So a healthy adult doesn't need to panic when hunger hits. Have some water, wait a bit, and the bell often fades by itself.

And when you're not hungry, is it OK to skip a meal? One review pooled thirteen trials: people who skipped breakfast ended up eating about two hundred sixty fewer calories a day, and didn't gain weight. The evidence isn't strong, though, and skipping meals won't make you slim either. In another trial, one group only ate between noon and eight p.m.; after three months, they weren't any thinner than people eating three meals a day. But there are two kinds of people who shouldn't do this.

First, older people and people who are ill. Their alarm clock can go quiet: they don't feel hungry, eat less and less, and slowly lose weight and strength. Among older people living at home, roughly one to three in ten are like this. Second, people taking diabetes pills or insulin. The medicine keeps lowering blood sugar even when they haven't eaten, so it can drop too low, leaving them dizzy and shaky. So here's the answer: hunger is an alarm clock, not a fuel gauge. A healthy adult can wait out hunger, and skipping a meal when you're not hungry is fine. But older people, sick people and anyone on diabetes medicine shouldn't wait to feel hungry: eat on time.

Which are you: the kind who's hungry right on the dot, or the kind who can forget to eat when busy?