Is intermittent fasting safe?

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Intermittent fasting - time-restricted eating windows or alternate-day patterns - has been studied enough to give a fair verdict: for most healthy adults it is safe, and it works about as well as ordinary daily calorie cutting for weight loss. The NIH's National Institute on Aging summarizes the research: fasting patterns show health benefits in studies, but they are not magic - the benefits track mostly with eating fewer calories overall, and long-term human data is still accumulating.

Who should not fast without medical guidance: pregnant or breastfeeding women, anyone with diabetes on medication - fasting plus insulin or sulfonylureas risks dangerous low blood sugar - people with a history of eating disorders, underweight individuals, teens, and older adults with frailty. If you take any medication timed with food, check before changing your eating window.

If you try it, the sensible version: a 10 to 12 hour overnight window - say 7 PM to 7 AM - is the gentle entry, keeps meals normal, and trims late-night snacking, which is where much of the benefit comes from. Keep protein and vegetables up inside the window, stay hydrated, and expect a week or two of adjustment hunger. Stop if you get dizzy, weak, or obsessive about the clock - the pattern should serve you, not rule you.

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