25/01/2026
How quickly do you gain fat after overeating?
Overeating happens to everyone. A meal out, a weekend away, a celebration, or just one of those days where things snowball. The question people usually ask me as a weight loss coach straight afterwards is simple and slightly panicked: how quickly does that turn into fat?
The short answer is not as quickly as you think.
Most short-term weight gain after overeating is down to food volume, glycogen and water retention rather than body fat. Actual fat gain tends to come from repeated surplus over days and weeks, not one meal or one day.
This is why reacting to the scale straight after overeating often causes more stress than progress. In most cases, the best response is to return to normal eating rather than trying to undo the damage.
For a full breakdown of what actually happens in the body, read the in-depth blog here:
https://www.simongpt.co.uk/how-quickly-do-you-gain-fat-after-overeating/
Worried a big meal has undone your progress? Learn how quickly fat gain happens after overeating, why the scales jump, and what matters.