What’s Driving America’s Obesity Problem?

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What’s Driving America’s Obesity Problem?

Currently, nearly two-thirds of Americans are overweight. By 2030 it is estimated more than half our population may be clinically obese. Childhood obesity has tripled, and most children will grow up to be overweight as well. The United States may be in the midst of raising the first generation since our nation’s founding that will have a shorter predicted life span than that of the previous generation.

The food industry blames inactivity. We just need to move more, they say. But what is the role of exercise in the treatment of obesity?

“There is considerable debate in the medical literature today about whether physical activity has any role whatsoever in the epidemic of obesity that has swept the globe since the 1980s.” The increase in calories per person is more than sufficient to explain the U.S. epidemic of obesity. In fact, if anything, the level of physical activity over the last few decades has actually gone up in both Europe and North America.

This has important policy implications. We still need to exercise more, but the priorities for reversing the obesity epidemic should focus on the overconsumption of calories (See How Much Exercise to Sustain Weight Loss?). American children are currently eating about an extra 350 calories (equal to about a can of soda and small fries), and adults are eating about an extra 500 calories (equal to about a Big Mac).  We’d have to walk two hours a day, seven days a week to burn off those calories. So exercise can prevent weight gain, but the amount required to prevent weight gain may be closer to twice the current recommendations. It’s more effective to stick to foods rich in nutrients but poor in calories: see my video Calculate Your Healthy Eating Score. It’s cheaper too, see Best Nutrition Bang For Your Buck.

Public health advocates have been experimenting with including this kind of information. One study found that fast food menus labeled with calories and the number of miles to walk to burn those calories appeared the most effective in influencing the selection of lower calorie meals.

Exercise alone may have a small effect, and that small effect can make a big difference on a population scale. A 1% decrease in BMI nationwide might prevent millions of cases of diabetes and heart disease and thousands of cases of cancer. But why don’t we lose more weight from exercise? It may be because we’re just not doing it enough. “The small magnitude of weight loss observed from the majority of exercise interventions may be primarily due to low doses of prescribed exercise.”

People tend to overestimate how many calories are burned by physical activity. For example, there’s this myth that a bout of sexual activity burns a few hundred calories. So you may think, “Hey, I could get a side of fries with that.” But if we actually hook people up and measure energy expenditure during the act (and the study subjects don’t get too tangled up with all the wires and hoses) it may be only close to the metabolic equivalent of calisthenics. Given that the average bout of sexual activity only lasts about six minutes, a young man might expend approximately 21 calories during sexual intercourse. Due to baseline metabolic needs, he would have spent roughly one third of that just lying around watching TV, so the incremental benefit is plausibly on the order of 14 calories. So maybe he could have one fry with that.

I previously touched on this in my video Diet or Exercise, What’s More Important For Weight Loss?

Don’t get me wrong–exercise is wonderful! Check out, for example:

-Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

34 responses to “What’s Driving America’s Obesity Problem?

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  1. Whole REAL food fills us up, while processed FAKE food make us hungry. The food industry puts all it’s energy into figuring out how to make us eat more of their products. The advertising gets us to try it, and the carefully choreographed textures, flavors, saltiness, sweetness keep us coming back for more. The goal is to create a “food” that almost, but doesn’t quite satisfy us.

    1. A market economy provides what people demand, not what makes them healthy – unless that also happens to be what they demand. If vegetables and fruit could be cheaply packaged, stored, and commoditized like potato chips and Fruit Loops, we would see commercials every day touting the health benefits of vegetables and fruits. Instead, we’re sold potato chips “made with whole grains” and Fruit Loops fortified with “essential vitamins”.

      Government is the natural fallback in this situation and it could do a lot to resolve our confusion, but unfortunately these days rather than responding to the actual needs of its citizens it responds to the multitude of special interest groups with their own causes to defend and dollars to donate. That means corporations and the organizations they fund acting to defend and increase their interests, which ultimately means corporate profits. Unfortunately it does not mean the average citizen who is going about the business of living their lives who wouldn’t know the first thing about collective action or organizing a political advocacy group in defense of their interests…let alone healthy eating. The average person doesn’t even know what his or her interests are.

      No, the public doesn’t stand a chance in this day and political environment…but for nutrition information and education sites like this one…assuming someone is lucky enough to stumble upon it and decide that it, rather than any of the myriad websites promoting one fad diet over another, contains information that will help them improve their health through healthy eating.

  2. I do a lot of exercise, walk easily about 15,000 steps a day and do biking 3-4 times a week….BUT I still eat a fair amount of crappy processed junk so I know where the problem is.

    We’ve all heard this before and it’s true; YOU CAN’T OUT EXERCISE A BAD DIET.

  3. I have found this idea to be absolutely on the money. I’ve been eating your way for several years now, but found myself gaining weight over the last year. Highly perplexed, I sort of reverted back to my salad only days. Although I couldn’t sustain this for more than a couple weeks, a few pounds slipped off. But I was hungry…so I decided to listen to you, stop snacking, move more, and eat at regular times. Now I’m like I was in the beginning of my plant journey. I eat more whole grains, seeds, and beans with fruit, salads, and veggie sides. I walk instead of ride whenever possible. Stand instead of sit. Do exercises that are interesting and encouraging. The pounds are slowly coming off. I am satiated. I don’t constantly think about food anymore.

    Watching your videos encourages me to stay on track without obsessing about the whole thing. Thank you so much for this beautiful gift.

  4. Focusing on diet and exercise as culprits of the obesity epidemic, while true, is myopic since it does not identify the ultimate cause: the steadily declining American quality of life. Right now the domestic work week is approaching 50 hours while for the French, Germans and Austrians, it is 35 hours per week. The average American has 6 hours per week free time after getting the basics done. Americans don’t know how to cook anymore and don’t have the time for it anyway. Obviously, they don’t have time for exercise either. The effective enslavement of the masses to the military industrial complex that former President Eisenhower warned us about has come true.

    A terrific book that documents this is “The Overworked American”:


    I trace this trend to the WWII Roosevelt Administration mobilization campaign to get women into the workforce typified by “Rosy the Riveter” propaganda:


    Subsequent campaigns to convince women they are not “fulfilled” unless they burn their bras and enter the workforce have done the rest. The obvious is ignored: If “Rosy” is going to rivet, then hubby must homemake or the quality of life declines for both.

    No solution to the health and obesity epidemic is possible until the quality of American life is improved to allow for it.

    1. I guess it depends on how you define free time. The average American watches 4-6 hours of TV per day according to AC Nielsen. If that doesn’t count towards their free time, and is just considered ‘the basics’, then, yeah, we’re kinda low on time.

      I’m a lazy salary man myself, but my wife works a lot of overtime. Even with the 50 hour work week, volunteering at church on Wednesdays, a bible study group on Mondays, church on Sunday, going to our son’s sporting events, shopping (because shopping is, apparently, essential) and a daily workout, she still has hours to waste on Pintrest every day.

      You are right that our busy lifestyle is part of the reason why we’re obese (we don’t take the time to make food and just grab whatever is ready), but it isn’t “The Man” who is making us busy.

    2. I’m on board. I think it stinks too that so many women who have children, the future of this country, are forced out into the work place to support them, and have to hire a someone to do the job they wanted of raising their own child at home! Other countries have found better ways, why can’t we? My son passed away and I “see” my remote grandchildren trying to cope with this situation, and it is heartbreaking when there isn’t much I can do so far away! Then they have to be latchkey kids sometimes, bigger kids watching little kids, eating and drinking whatever…it’s nobody’s fault per se, but it is NOT healthy in any respect, and very stressful for everyone!

    3. I’m going to have to disagree. I think Americans have the time, they just don’t prioritize for it. We all have the same 24 hours in a day. How is it that a single parent working 2 jobs still manages to find the time to cook and eat healthy AND workout 30 minutes a day? The answer is because that is where their priority lies. Excuse will do wonders for a lazy person. Stop the excuses and find results.

  5. As we know, the message to the public can’t just be based on cutting calories. There has to be some part of the message that focuses on whole food sources vs processed foods.

  6. Why don’t you talk about the toxicity and addictive additives in foods instead of exercise. Everybody knows we are being fed anything but real food.

  7. and perhaps people don’t know what to replace the unhealthy diet with? Once on a plant based whole food diet it’s quite important to learn a new range of cooking skills in order to stick with it, or you’ll give up and go back to processed food. Maybe education needs to be part of the equation as well.

    1. Totally agree, not just about the cooking, but all the new food choices and eliminating the old ones…and just all the change! Anyone who expressed interest in a plant based diet quickly felt overwhelmed by the dramatic changes that felt so unfamiliar, no matter how simple they seemed…I always try to give tips and links to basic, simple recipes, and step by step approaches like the 21 day challenge or the like, where they walk you through it one day at a time! Crazy but true. I think we are truly creatures of habit and that is why so many of us get stuck in our bad, but familiar ruts…and don’t really want to change! LOL! I know that was true for me for all but the last 5 years!

      1. yes if it feels like you’re depriving yourself people won’t be able to stick with it. I needed to workout the balance of each meal ie how to incorporate a plant based protein (and how to make it appetizing) No one is going to last if it tastes like cardboard. I also had to get used to the bulk of vegetables we needed to purchase. I liked the Engine 2 diet book while trying to figure out the new way of planning groceries and putting together meals in the beginning. Then you develop your own meals gradually.
        but you know you’ve made progress when you feel ill watching a cooking program using dairy/animal protein/ mountains of sugar and you have to switch the channel !
        Or trying a biscuit after several months and not enjoying the taste anymore, and realizing that you really prefer the taste of fruit /nuts/dried fruit now. My sense of smell and taste buds changed as well. I also did not feel hungry as often as I used to , and it leveled out.
        I agree that you have to tackle it one day at a time , it became natural for the whole family after about 5- 6 months.

        1. Good for you getting the whole family on board! It was just me and my husband, who lost his leg to diabetes and poor self care. Not wanting the same fate, I got on board with the WFPB diet, reversed many illnesses and my own life-long struggle with obesity. I am a total convert, I wish I could say the same for him. His habits rule him and I have to realize you can lead a horse to water…but…you know.

          1. It’s great to have the extra energy isn’t it? It is amazing you were able to free yourself from the life-long struggle with obesity. Eating habit is the hardest thing to change because unlike drugs/toxins etc we actually need food. I think I am almost there with reversing my blood glucose problems but I am still needing to tweak things.
            Habits are really hard to break so I can see why it’s hard for your husband, I still crave for certain things too, but of course we do wish our partners and ageing relatives will make the switch so they can avoid future illnesses. Sometimes children are better at adapting so they kind of lead us too in a way.

            1. The diet mentality I had always been taught…caloric restriction and portion control, are doomed to fail by their very nature. Feeling sated is a biological drive that asserts itself and defeats the best of intentions, causing enormous self hatred at one’s perceived “failure” and weakness, time and time again. I “dieted” my way to over 300 lbs, ate so little, and still could not lose weight, even with exercise. Everyone else assumes you just pig out all day and lay around, that just adds to the self esteem issues. I wish I had learned about the WFPB lifestyle so much earlier in life, because that was the key to all my problems, (as I’m sure it would be for most anyone) but better late than never!

  8. Its pretty obvious that its not physical activity but poor diet. Kitchen workers are active most of their days yet many are obese.

    1. I work in a kitchen. I was obese for many years. Just standing up all day did not help me lose weight. I finally got a grip on my weight when I started bicycling to work everyday. I lost 95 pounds that way. Just standing up all day does not raise one’s heart rate. Raising one heart rate during exercise is what can really help with weight control. Riding up hills on a bike raises one’s heart rate I couldn’t eat ALL that I wanted and still lose weight by exercise, but my diet didn’t have to be nearly as draconian as it would have been had I not exercised everyday. Anyway, I haven’t gained back even one pound in 5 years and I have actually lost 10 more. Even after the 95 pound weight loss, I was already in the normal weight range. I have continued to exercise everyday and have steadily improved my diet. I don’t eat meat at all and eat far fewer sweets than I used to. Now, I might be getting too thin. So, exercise DOES help with weight control at the right amount and with SOME control of diet- it does lessen the severity of the control needed. It also helps a lot to eat plants, because the fiber contained in it is very conducive to weight control as well. Eating only whole foods and not processed foods also helps a lot as well. To me, it is not either/or but both/and. It also isn’t a matter of going to the gym, but incorporating activity into one’s daily living, such as by bicycling to work. Also fixing one’s own meals is very helpful. I only go out to eat once every two weeks.

  9. I am beginning my dissertation for my PhD program about August and am doing the dissertation on obesity and cognition. I would love to discover some of the study resources you cite to add to my lit review. Thank you.

    1. Hi Marjorie. Good luck on your project! All citations are listed within each hyperlink on this blog post. Let me know if any of them do not work. Also, you’ll find the “sources cited” button under each video title helpful for Dr. Greger’s references. Lastly, you may find some great citations from our obesity page. Or even more when searching for cognition. You may be preoccupied for a few days :) Best of luck let us know how we can help!


    2. The US food supply statistics may throw some light on the background to obesity. For example in 1909 when figures began, the food supply equated to about 3,400 kcalories per person per day. In 2010, the last year for I’ve seen figures, it was 4,000 kcalories per person per day. Saturated fat was 50 (grams I think) per person per day in 1909 and 59 in in 2010. It reached a high of 64 in 2002 and 2003. Carbohydrate fell from 499 in 1909 to 474 in 2010 and fibre from 29 to 25 while cholesterol rose from 440 to 460.


  10. The Pleasure Trap by Doug Lisle explains a lot for me. It’s similar to alcoholism or drug addiction. Today’s food evidently simply provides too much of a pleasure shot, it’s so hard to say no to more. So, get it out of the house and don’t go to restos or places where that’s all they serve. We can relearn how to eat.

  11. Cell’s ability to store fat is an evolutionary survival adaptation. Researchers need to focus on the genes that allow cells to store fat so that we can escape the flood of phony miracle diets and miracle lifestyle and nutritional cures that are endlessly being peddled to a frustrated ad gullible Public..

  12. I recently heard a talk about the effect of glyphosate (Monsanto’s roundup) in the food supply causing a hormone disruption. In as small as parts per trillion!!!These pollutants cause obesity. In higher concentrations they cause cancer, infertility, etc…
    Check out Stephanie Seneff MIT professor and her talks about this chemical…. Avoid Glyphosate, eat non-GMO and organic.

  13. Americans and people of most nations are systematically socialized to eat unhealthy, and are systematically hindered from getting knowledge about what is healthy. Even the pediatricians that children go to, which usually are grossly overweight themselves, and hence very bad role models, participate in this bad socialization program. Some knowledge:

  14. The single largest line item health care cost is obesity which assesses approximately (currently, and growing) $147 Billion in cost annually in the USA alone. These costs are shared burdens and the actuarial tables are irrefutable. We’re all paying for them. Shaming worked on smokers, it’ll work on others just as well. The cost is growing each year and it’s eclipsed smoking as the #1 health issue in America. It’s a lifestyle choice and they should focus on being a reasonable size so they can avoid:

    Cancer; Knee/hip replacement; Upper GI/Lower GI issues, Diabetes, high blood pressure, heart disease, COPD, using a mobility scooter etc etc. A simple lifestyle change of eating less and moderate exercise and, presto, the weight will come off.

    25 years ago only a very small group of people had heard of bariatric chairs, bariatric toilet seats, beds built for fat people, bariatric MRI and CAT Scan machines and now it’s commonplace. It’s getting past the point of being ridiculous.

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