Is obesity inevitable? [Updated]
The vast majority of overweight and obese Americans will not lose sufficient weight -- and obesity won't be prevented -- without major changes in society, say the authors of a thoughtful, although bleak, commentary published today in the Journal of the American Medical Assn.
The piece, by Martijn B. Katan of VU University, Amsterdam, and Dr. David S. Ludwig of Children's Hospital, Boston, should not deter people who have resolved to eat healthier and exercise more in the new year. However, it points out some hard truths about weight loss and American's obesity epidemic. [Note: A previous version of this post described Katan as employed by the University of Amsterdam. He is with VU University, Amsterdam.]
For example, the authors explain, when an individual reduces food intake and his or her body size diminishes, so does the amount of energy needed to maintain and move it. "Therefore, additional weight loss can only be achieved by a more severe diet or a more arduous physical activity routine," they write. "Most individuals do the opposite: After having achieved some weight loss, they resume their original diet and exercise habits. Consequently, weight gain recurs rapidly."
The second problem: Most Americans consume far too many calories, resulting in a hefty weight gain over time. For example, they say, drinking 1 ounce of a soda and walking one minute less per day creates a temporary energy surplus of about 13 calories a day. That sounds small. But repeating changes of this magnitude over 28 years would produce a 35-pound weight gain. Some studies have shown the average American today consumes about 500 calories per day more than they did in the 1970s.
The point to this depressing analysis, the authors say, is to clarify that modern lifestyles contribute significantly to obesity and that it will be nearly impossible to reverse obesity trends on a grand scale without major societal changes.
"[S]mall changes in lifestyle would have a minor effect on obesity prevention," they write. But the huge energy imbalance most Americans experience is "far beyond the ability of most individuals to address on a personal level." Instead, they say, changes in the food supply and social infrastructure and more stringent regulations of the food industry will be needed.
Katan elaborated in an e-mail: "Studies show that even the most motivated, thoughtful, strong-willed people have a hard time losing weight when huge portions of cheap, tasty, convenient food are available at every turn of the road, and when walking and other forms of exercise are superfluous or impossible."
Food for thought.
-- Shari Roan
Photo credit: Rogelio V. Solis / AP