Overweight is unhealthy, but fat people who lose weight may actually become even more unhealthy. That’s the devilish dilemma facing millions of fat people. In 2005 Danish and Finnish epidemiologists showed that, in the worst-case scenario, fat people who lose weight almost double their mortality risk.
The researchers followed just under three thousand fat Finns – with a BMI of over 25 – born in 1958. In the 1970s some of the people in the group had attempted to lose weight. Some were successful and others weren’t. The researchers had data on the group up to the late 1990s.
By 1999 some of the Finns had died. The researchers discovered that two groups had a markedly higher risk of mortality: the fatties who had successfully lost weight in the 1970s and the fatties who had not tried to lose weight and had become even heavier. HR = chance of dying.
The figure immediately below shows the survival rate among the fat Finns that wanted to lose weight. The dieters who didn’t lose weigh weight were healthiest. In the lower figure you see the survival rate of the fat people who did not try to lose weight. In this group it was the fatties with a stable bodyweight who were healthiest too.
The fat people who lost weight by exercising more – probably Finns who started jogging – were in slightly better condition than Finns who only lost weight by dieting.
Healthy weight loss is not just about getting rid of kilos, but about achieving a body composition of little fat and lots of muscle. The fat Finns in the study probably became less healthy because they lost lean body mass.
Intention to lose weight, weight changes, and 18-y mortality in overweight individuals without co-morbidities.
Weight loss in the obese improves risk factors for cardiovascular diseases and diabetes. However, several studies have shown inconsistent long-term effects of weight loss on mortality. We investigated the influence on mortality of intention to lose weight and subsequent weight changes among overweight individuals without known co-morbidities.
METHODS AND FINDINGS:
In 1975, a cohort of individuals reported height, weight, and current attempts (defined as “intention”) to lose weight, and in 1981, they reported current weight. Mortality of the 2,957 participants with body mass index > or = 25 kg/m2 in 1975 and without pre-existing or current diseases was followed from 1982 through 1999, and 268 participants died. The association of intention to lose weight in 1975 and actual weight change until 1981 with mortality was analysed while controlling for behavioural and psychosocial risk factors and hypertension as possible confounders. Compared with the group not intending to lose and able to maintain stable weight, the hazard ratios (with 95% confidence intervals) in the group intending to lose weight were 0.84 (0.49-1.48) for those with stable weight, 1.86 (1.22-2.87) for those losing weight, and 0.93 (0.55-1.56) for those gaining weight. In the group not intending to lose weight, hazard ratios were 1.17 (0.82-1.66) for those who did lose weight, and 1.57 (1.08-2.30) for those gaining weight.
Deliberate weight loss in overweight individuals without known co-morbidities may be hazardous in the long term. The health effects of weight loss are complex, possibly composed of oppositely acting processes, and need more research.
PMID: 15971946 [PubMed – indexed for MEDLINE] PMCID: PMC1160579 Free PMC Article