Lose Weight and Live Longer! Does it Work?

The question of whether intentional weight loss improves health of the obese is important, given the high prevalence of intentional weight loss in our society. Dieting and especially yo-yo weight changes are common though the number of studies suggest that both weight loss and weight fluctuation are associated with a DECREASED life span! However, a closer look at these studies indicated that the decrease in longevity might correspond to reasons other than weight loss per se.

A study controlled for smoking and pre-existing illness, found that intentional weight loss by overweight, white, US women, consistently reduced mortality in those with obesity related diseases.

An Indian study, involving individuals with previous myocardial infarction, found   that a proper diet  reduced risks of death. Those losing > 5 kg had the greatest reduction in both total and cardio-vascular mortality. In both the above   studies, weight loss was approximately 10% of initial body weight.  -- International Journal of Obesity & Related Metabolic Disorders. 21 Suppl 1:S14-9; discussion S20-1, 1997

What happens when overeating is prevented. Longevity in obese and lean male and female.

This is experimental data and should be considered with coution but it makes one think about our human beings eating habits.

Obese and lean rats were fed a protein diet with only one limitation. Obese rats were fed exactly the same amount of calories that the lean controlsconsumed with free access to food.

Lean overeating rats had longer life spans than did obese rats. Preventing overeating increased maximum life span in both obese males and females and decreased deaths caused by kidney diseases.

Even a smaller restriction in  energy intake (8-18%) required to prevent overeating compared with the 35-40% in most studies on energy restriction produced similar increases in longevity, suggesting that the obese are particularly sensitive to energy restriction.

It was very interesting fact that percentage of body fat in food-restricted obese rats did not differ from that of the obese fed freely. It meant that the well know phenomenon of reduced longevity is not the result of obesity per se, but rather is influenced by resulting (or causing!) metabolic pathologies.  -- American Journal of Clinical Nutrition. 66(4):890-903, 1997

Obesity, alcohol, smoking, and mortality.

The goals of this study conducted by Marshfield Medical Research Foundation, Marshfield Clinic, WI, were to assess the impact of obesity, alcohol use, and smoking or  two or more of these risk factors on elevated risk of mortality. The researchers studies 8006 Japanese-American men living in Hawaii. After 22 years of follow-up (nearly 159,000 person-years of observation,) 2667 deaths from all causes were identified.

There was a J-shaped relation between BMI and all-cases mortality which means that not only excessive weight but also underweight caused an increase in mortality. Specifically, men who had the lowest body mass (BMI < 21.21) and drank moderately to heavily (>25 oz per month)    experienced a 63% excess risk  compared to men who had intermediate  body mass (21.21 - 26.30) and drank occasionally to lightly (0.01 - 24.99 oz per month).  There was no significant interaction for BMI and cigarette smoking, for alcohol and cigarette smoking, or for the three factors combined.

The most important finding of this study was that, in addition to confirming that cigarette smoking could shorten life, extreme (high AND low)  BMI values and high alcohol consumption are each potentially harmful to health, but even more so if moderate or heavy drinking is concomitant with low body mass, a possible indicator for low intake of nutrients. --  Annals of Epidemiology. 7(4):311-7, 1997

The heaviset Japanese live longest lives but for the price of the quality of life.

     
The mean age of the  time of death was significantly higher in the overweight group than in the lean group.  There were no differences in the incidence of severe atherosclerosis.     Patients in the overweight group were bedridden for a significantly longer time than those in the lean group. We conclude that body weight in the elderly is   positively associated with survival. However, overweight subjects suffered from non-fatal cerebral infarction, and prolonged survival was associated with greater  disability --  Journal of the Nippon Medical School. 62(3):231-40, 1995