People who are already overweight might eat less because their body doesn’t feel hungry — so it’s not that eating less makes you fat, it’s that being fat makes you eat less.
Evidence from Studies
Supporting (2)
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When the body can't respond to the 'full' signal from leptin, it still eats less — which means obesity might cause reduced eating, not the other way around.
When rats are leptin-resistant, they eat less; fixing that resistance makes them eat more — proving that fat-related hormone problems can cause less eating.
Contradicting (4)
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This study found that people who ate fewer meals per day tended to lose weight, but it didn’t look at whether being overweight or having metabolic problems made them eat less — so it doesn’t support the idea that body fat causes people to eat less.
Early Time-Restricted Feeding Reduces Appetite and Increases Fat Oxidation but Does Not Affect Energy Expenditure in Humans
This study found that eating earlier in the day makes people feel less hungry, but it didn’t look at whether being overweight or having hormone problems causes people to eat less — so it doesn’t support the claim that fat and hormone issues lead to reduced appetite.
These rats get fat even though they don’t eat more — so fat gain doesn’t always come from eating more, and doesn’t always make you eat less — breaking the link the assertion assumes.
When hamsters lose fat, they don’t get the health benefits from a hormone that normally helps metabolism — meaning fat isn’t just a problem; it’s needed for the body to work right, so it can’t be causing less eating.