The longer you go without eating at night, the less weight you tend to carry — not because fasting burns fat magically, but because it naturally reduces total food intake.
Evidence from Studies
Supporting (3)
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People who went without eating for 18+ hours overnight tended to lose weight or gain less weight over time, likely because they ate fewer calories overall.
People who went longer without eating at night were less likely to be overweight, even when researchers accounted for what they ate during the day — meaning long overnight fasts might help people stay lean.
This study found that people who fasted overnight for a long time (more than 18 hours) tended to have lower body weight, which supports the idea that long fasting helps people lose weight.
Contradicting (2)
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Fasting during Ramadan didn’t make teens lose weight unless they also learned how to eat better — so fasting alone doesn’t seem to be enough to lose weight.
People who ate more often and had shorter fasts at night actually had better diets and didn’t weigh more — so long overnight fasts don’t seem to help people lose weight.