This is a guest blog post by Daniel Green.
In her August 21 New York Times Slipstream column, Natasha Singer opens
“WHY are Americans getting fatter and fatter? The simple explanation is that we eat too much junk food and spend too much time in front of screens — be they television, phone or computer — to burn off all those empty calories.”
Now I agree that, as a population, we are eating too much, but is exercise really the solution to America’s growing obesity epidemic?
Consider the following example: at a recent trip to McDonald’s you consume a Chocolate Triple Thick Shake, of which even the ‘small’ 16oz version contains 580 calories according to McDonalds.com. Expending that same amount of energy would take about an hour if you jogged at a briskly 5mph pace (580calories x 1mile/100 calories x 12minute/1 mile for those of you who want to see the math). Now it probably didn’t take you an hour to drink the shake, even if you were sipping it on the ride over to soccer practice.
Weight balance is largely determined by the law of thermodynamics which states that
Change in Bodyweight = Change in Energy Intake minus Change in Energy Expenditure.
So if we want to lose weight, we either need to decrease energy intake (eat less) or increase energy expenditure (move more). According to Coca Cola CEO Muhtar Kent, Americans are just lazy. But is the CEO of the largest soft drink company in the world really a trusted source for advice on reducing obesity? I don’t think so, especially seeing as how ‘lazy people’ funded his earnings of nearly $20M in 2009.
As seen from NHANES data (see figure above), food intake and obesity rates are directly correlated. Starting around the late 80’s food intake and obesity rates sky rocketed, but why? There are a lot of causes:
- food prices dropped as a result of aggressive farm subsidies,
- food availability increased (even Auto Zone, the automotive retail chain, now sells a wide range of snack mixes and roasted nuts!),
- and the elephant in the room - increasing portion sizes.
A 2009 study by the Cornell Food and Brand Lab compared 18 recipes that had been published annually in the “Joy of Cooking,” inarguably one of the most read cookbooks of all time. Between 1936 and 2006 calories per serving jumped 63 percent on average.
While exercise may not have as much direct influence on bodyweight as we’ve been taught, it is still an important part of a healthy lifestyle. But if on January first you find yourself making the same weight loss resolution you’ve made every year for the last decade, consider making a conscious effort to eat less before going out and buying another diet book that will just collect dust on a shelf or spending $750 to renew the gym membership you use maybe once a month.
Daniel Green is an Applied Nutrition and Psychology major and Food Psychology researcher at Cornell University. He is also the Founder and Interim-CEO of Dynamic Automated Nutrition Innovations, an Ithaca-based startup that focuses on finding innovative solutions to global obesity. He can be reached at dpg64 at Cornell dot edu.