Do you eat less when you eat slowly?

Short answer

Yes. Eating slowly and chewing more cut that meal by about 10-15%, with no extra hunger. Over 2 weeks on meals that are eaten slowly, people ate 369 kcal less a day.

Do you eat less when you eat slowly?
'Slower → fullness signals catch up → you eat less' — is that right?
A common tip says to eat slowly because the feeling of fullness arrives late. We checked whether people really eat less, and whether they get hungrier or eat more later to make up for it.
People ate less in that meal
Pooling 22 studies, slow eaters ate less
An analysis that pooled 22 studies that changed eating speed found people ate less when eating slowly. In a trial where 30 people ate as much as they wanted of the same food, they ate 646 kcal fast and 579 kcal slowly — about 10% less.
More chewing cut it further
Chewing 2 times as much meant eating 15% less
When 45 people ate pizza until full, chewing each bite 1.5 times their usual count cut intake by 9.5%, and 2 times cut it by 14.8%. More chewing made meals longer and eating slower.
They ate less but weren't hungrier
No difference in hunger right after or 3.5 hours later
The analysis of 22 studies found eating speed made no difference to hunger at the end of the meal or 3.5 hours later. In the 30-person trial, the slow meal — which was smaller — actually left people fuller right after.
The effect happens while you eat
With a fixed portion, the next meal didn't change
In a trial where 25 people ate the same fixed meal in 7, 14 or 28 minutes, how much they ate at the next meal did not differ. The benefit of slow eating comes not after a set amount, but from putting the fork down earlier during the meal.
It held for 2 weeks
369 kcal less a day and 0.43 kg less body fat
41 people spent 2 weeks each on meals with textures that are eaten slowly and meals that are eaten fast. On the slow meals they ate 369 kcal less a day, the gap held day after day, and body fat dropped 0.43 kg. Body weight did not differ over the 2 weeks.
Over 1 year, weight measures changed too
Slowing down cut meal size by 45 g
When 106 young people aged 9-17 slowed down for 12 months using a device that shows eating speed, their BMI and body fat fell more than with standard care alone, and meal size dropped by 45 g. The difference was still there at 18 months.
Bottom line: eat slowly, eat less
About 10-15% less per meal, without hunger
Eating slowly and chewing more cut a meal by about 10-15% with no extra hunger. The effect happens within the meal and held for 2 weeks. Chewing each bite 1.5-2 times your usual count is enough.