BMI & Mortality

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" The relative risk (RR; 95% CI) for non-cancer mortality during

follow-up was higher in men with decreasing BMI in all subgroups: RR

2.64 (1.46-4.71, baseline BMI <21 kg m(-2)), 1.39 (0.98-1.95, baseline

BMI 22-25 kg m(-2)), and 1.71 (1.18-2.47, baseline BMI 26+ kg m(-2)),

using BMI-stable men as reference group. "

I wonder what is amiss here...

The enigma of increased non-cancer mortality after weight loss in

healthy men who are overweight or obese.

Nilsson PM, Nilsson JA, Hedblad B, Berglund G, Lindgarde F.

Department of Internal Medicine, University Hospital, Malmo, Sweden.

peter.nilsson@...

OBJECTIVE: To study effects on non-cancer mortality of observational

weight loss in middle-aged men stratified for body mass index (BMI),

taking a wide range of possible confounders into account. DESIGN:

Prospective, population based study. SETTING: Male population of

Malmo, Sweden. PARTICIPANTS: In all 5722 men were screened twice with

a mean time interval of 6 years in Malmo, southern Sweden. They were

classified according to BMI category at baseline (<21, 22-25,

overweight: 26-30, and obesity: 30+ kg m(-2)) and weight change

category until second screening (weight stable men defined as having a

baseline BMI +/- 0.1 kg m(-2) year-1 at follow-up re-screening). MAIN

OUTCOME MEASURES: Non-cancer mortality calculated from national

registers during 16 years of follow-up after the second screening.

Data from the first year of follow-up were excluded to avoid bias by

mortality caused by subclinical disease at re-screening. RESULTS: The

relative risk (RR; 95% CI) for non-cancer mortality during follow-up

was higher in men with decreasing BMI in all subgroups: RR 2.64

(1.46-4.71, baseline BMI <21 kg m(-2)), 1.39 (0.98-1.95, baseline BMI

22-25 kg m(-2)), and 1.71 (1.18-2.47, baseline BMI 26+ kg m(-2)),

using BMI-stable men as reference group. Correspondingly, the

non-cancer mortality was also higher in men with increasing BMI, but

only in the obese group (baseline BMI 26+ kg m(-2)) with RR 1.86

(1.31-2.65). In a subanalysis, nonsmoking obese (30+ kg m(-2)) men

with decreased BMI had an increased non-cancer mortality compared with

BMI-stable obese men (Fischer's test: P=0.001). The mortality risk for

nonsmoking overweight men who increased their BMI compared with

BMI-stable men was also significant (P=0.006), but not in

corresponding obese men (P=0.094). CONCLUSIONS. Weight loss in

self-reported healthy but overweight middle-aged men, without serious

disease, is associated with an increased non-cancer mortality, which

seems even more pronounced in obese, nonsmoking men, as compared with

corresponding but weight-stable men. The explanation for these

observational findings is still enigmatic but could hypothetically be

because of premature ageing effects causing so-called weight loss of

involution.