You've probably heard it before: "Try not to eat more than seven times a day."
But why? What actually happens in your body — and in your mouth — when you keep snacking throughout the day?
The answer involves two things happening at the same time: something in your blood, and something in your mouth.
Imagine you eat a chocolate bar or drink a glass of cola. The sugars are absorbed quickly. Your blood sugar rises[1].
Your body responds by releasing insulin — a hormone that moves sugar out of your bloodstream and into your cells. Sometimes that response is a bit too strong. Your blood sugar drops fairly quickly afterwards.
That can leave you feeling hungry, shaky, or tired. Or craving something sweet again.
So you grab another snack. Your blood sugar rises again. Then drops again. And so the cycle repeats.
Your body can use some sugars immediately — for energy in your muscles and brain. But if you regularly take in more than your body needs, that surplus has to go somewhere.
Part of it gets converted into fat reserves[2]. That made sense for our ancestors, who needed stored energy to survive times without food. The problem is that food is now available all day long. So those reserves are used less often.
That doesn't mean a single sweet snack instantly "turns into fat." The process is more gradual than that. But regularly eating more energy than your body uses does contribute to weight gain over time.
Something similar happens in your mouth every time you eat or drink.
Bacteria in the mouth use sugars as fuel and produce acids. Those acids temporarily lower the pH in your mouth, which softens the enamel on your teeth. This is called demineralisation[4].
Luckily, your saliva helps. It neutralises the acids and restores minerals to the enamel. That process is called remineralisation.
But recovery takes time — usually between 20 and 60 minutes[5,6].
Soft drinks are difficult for teeth because they often contain both sugar and acid.
Cola contains phosphoric acid. Many other soft drinks and iced teas contain citric acid. Even sugar-free versions can damage enamel — because the acidity remains[8,9,10].
Energy drinks are especially harsh on teeth. They combine high acidity with large amounts of sugar. Some also contain high doses of caffeine and taurine[11,12].
The pH of energy drinks often falls between 1.5 and 3.3 — nearly as acidic as stomach acid[13]. Tooth enamel dissolves rapidly with repeated exposure.
Seven isn't a magical number. Eating eight times one day won't suddenly ruin your health or your teeth.
The idea is simply that your body and your mouth need recovery time between eating moments.
Between meals and snacks:
Water. Plain water.
It doesn't affect your blood sugar and doesn't make your mouth acidic. Tea and coffee without sugar are generally fine too.
You don't have to avoid every snack or never drink soda again.
The point is to understand what happens in your body and in your mouth when you eat or drink constantly throughout the day.
Give your body some rest between eating moments. Your blood sugar stays more stable. Your teeth have time to recover.
That's the main idea behind the advice.