Mixed
Among middle-aged women who have never smoked and maintained stable weight, higher body-mass index (BMI) is directly associated with increased all-cause mortality, with the lowest mortality observed in lean women (BMI < 19.0).
For middle-aged women who have never smoked, maintaining a stable, lean body weight (BMI < 19.0) is associated with the lowest risk of death from all causes, particularly cardiovascular disease and cancer. Avoiding significant weight gain since young adulthood (age 18) is also critical, as gaining 10kg or more increases mortality risk. The perceived safety of being 'overweight' is largely an artifact of smoking and pre-existing illness in other studies.
Body weight and mortality from all causes were directly related among these middle-aged women. Lean women did not have excess mortality. The lowest mortality rate was observed among women who weighed at least 15 percent less than the U.S. average for women of similar age and among those whose weight had been stable since early adulthood.
Why this rating
Large prospective cohort (N=115,195), long follow-up (16 years), rigorous exclusion of confounders (smoking, pre-existing disease, weight loss).
Source
Body Weight and Mortality among Women
JoAnn E. Manson et al. · New England Journal of Medicine · 1995
This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →