The claimEvidence B · meta-analysis
Even drinking water makes you fat
The evidence
Water has zero calories and cannot become fat. A 1-2 kg daily swing is water: glycogen holds 3-4 times its weight in water (Olsson & Saltin 1970), plus sodium retention and hormones. Watch the 2-week trend.
The mechanism, in brief
Glycogen binds water, and sodium holds on to water. The extra 1–2 kg on the scale when you wake up is almost always one of those two, not fat.
Sources (2)
- Olsson, K. E., & Saltin, B. (1970). Variation in total body water with muscle glycogen changes in man. Acta Physiologica Scandinavica, 80(1), 11-18. About 3-4 g of water is stored with each gram of muscle glycogen; a carbohydrate-rich diet raised total body water by ~2.2 L, attributed to glycogen storage.
- National Academies of Sciences, Engineering, and Medicine. (2019). Dietary Reference Intakes for Sodium and Potassium. National Academies Press. The PubMed book abstract (PMID 30844154) gives no reference values; it says the report updates the sodium and potassium DRIs with an expanded model that adds chronic-disease endpoints (the Chronic Disease Risk Reduction Intake). The numeric AIs and CDRRs were not re-read for this note (abstract).