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Obesity Erodes Smoking Cessation Gains in US

Over the past 15 years, smoking rates in the US have declined by 20%, whereas obesity rates have increased by 48%.

A new analysis published in the New England Journal of Medicine by Susan Stewart and colleagues from Harvard University, Boston, MA, forecasts the effect of trends in obesity and smoking on future U.S. life expectancy and quality-adjusted life expectancy.

The researchers used data from the past three decades to forecast future rates of obesity and smoking and estimate their effects on length and quality of life.

The net effect of the declines in smoking and the increases in BMI for an 18-year old is a reduction in life expectancy of 0.71 years and a reduction in quality-adjusted life expectancy of 0.91 years relative to the trend. This pattern of results is seen for every year between 2005 and 2020 and becomes more pronounced over time.

The calculations assume that if past trends continue, almost half the U.S. adult population will meet the WHO criteria for obesity by 2020 (currently the obesity rate already exceeds 35% in some states).

Obviously, these forecasts are at a population level and do not apply to a particular person who loses weight or stops smoking.

While these results do not imply that life expectancy will fall, they do suggest that as a result of increasing obesity rates life expectancy will rise less rapidly than it otherwise would.

While these are US data, there is little reason to assume that similar trends will not also be apparent in other countries including Canada.

Clearly, policy makers will likely now need to address obesity with the same vehemence as they did smoking – unfortunately, finding and implementing effective policies to reduce obesity makes smoking bans look like a walk in the park (no pun intended).

Edmonton, Alberta


  1. Suggestion: the Canada Food Guide should include calories.

    See past posts on Yoni Freedhof’s Weighty Matters blog on this topic (A colleague of Dr Sharma, I think)

    People should know how many calories a day they need.
    Yes there are some people who can’t handle that. A friend of mine with a learning disability never learned to count over 20. Most people can handle adding numbers up to 2000 or 3000. A simple web-based calculator can give people an approximate daily calorie level, which they can then adjust if they gain or loose weight at that level.

    The food guide already gives some nutrition information as % of daily requirement for a person eating 2000 calories a day. If you eat 1800 calories a day , or 2500 calories a day, you have to calculate % daily requirement by the ratio of your calorie intake to the 2000 calorie standard. It is comparatively easy to add up calories to your personal level.

    These days this is really important because manufacturers are able to create incredibly high calorie food, and advertisers make it seem normal to eat large portions of high calorie food – pastry with icing for a child’s breakfast, combinations of fast food any one of which has enough calories for a whole meal, salads with more calories than burgers, brocolli being inedible unless it’s covered with cheese, 100 calorie treat packs as if 100 calories of no food value is inconsequential, one individual restaurant dessert which has enough calories for a whole day’s food, “low-fat” food having extra sugar added so calories are the same or more.

    Of course not everybody will track every calorie. But everybody should know that if you need 2000 cals a day, a 500 cal fancy coffee and a 500 cal muffin is half your entire days food. An 80 cal plain coffee with milk and a 300 cal chicken snack wrap is less likely to add pounds. No mystery. Why is the Canada Food Guide not helping Canadians get savvy with this?

    Excess calorie intake is a major cause of one of the worst health problems we have – obesity. It is criminal for the Canada Food Guide to fail to address this directly.

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  2. % daily requiremnt is on food labels, not the canada food guide

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