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    Americans Are Fat Because They Eat Too Much, Not Because Of No Time To Exercise
    By News Staff | May 8th 2009 12:30 AM | 5 comments | Print | E-mail | Track Comments
    New research that uses an innovative approach to study, for the first time, the relative contributions of food and exercise habits to the development of the obesity epidemic has concluded that the rise in obesity in the United States since the 1970s was virtually all due to increased energy intake. 

    How much of the obesity epidemic has been caused by excess calorie intake and how much by reductions in physical activity has been long debated and while experts agree that making it easier for people to eat less and exercise more are both important for combating it, they debate where the public health focus should be.

    A study presented on Friday at the European Congress on Obesity is the first to examine the question of the proportional contributions to the obesity epidemic by combining metabolic relationships, the laws of thermodynamics, epidemiological data and agricultural data.

    “There have been a lot of assumptions that both reduced physical activity and increased energy intake have been major drivers of the obesity epidemic. Until now, nobody has proposed how to quantify their relative contributions to the rise in obesity since the 1970s. This study demonstrates that the weight gain in the American population seems to be virtually all explained by eating more calories. It appears that changes in physical activity played a minimal role,” said the study’s leader, Professor Boyd Swinburn, chair of population health and director of the World Health Organization Collaborating Centre for Obesity Prevention at Deakin University in Australia.

    The scientists started by testing 1,399 adults and 963 children to determine how many calories their bodies burn in total under free-living conditions. The test is the most accurate measure of total calorie burning in real-life situations.

    Once they had determined each person’s calorie burning rate, Swinburn and his colleagues were able to calculate how much adults needed to eat in order to maintain a stable weight and how much children needed to eat in order to maintain a normal growth curve.

    They then worked out how much Americans were actually eating, using national food supply data (the amount of food produced and imported, minus the amount exported, thrown away and used for animals or other non-human uses) from the 1970s and the early 2000s.

    The researchers used their findings to predict how much weight they would expect Americans to have gained over the 30-year period studied if food intake were the only influence. They used data from a nationally representative survey (NHANES) that recorded the weight of Americans in the 1970s and early 2000s to determine the actual weight gain over that period.

    “If the actual weight increase was the same as what we predicted, that meant that food intake was virtually entirely responsible. If it wasn’t, that meant changes in physical activity also played a role,” Swinburn said. “If the actual weight gain was higher than predicted, that would suggest that a decrease in physical activity played a role.”

    The researchers found that in children, the predicted and actual weight increase matched exactly, indicating that the increases in energy intake alone over the 30 years studied could explain the weight increase. 

    “For adults, we predicted that they would be 10.8 kg heavier, but in fact they were 8.6 kg heavier. That suggests that excess food intake still explains the weight gain, but that there may have been increases in physical activity over the 30 years that have blunted what would otherwise have been a higher weight gain,” Swinburn said.

    “To return to the average weights of the 1970s, we would need to reverse the increased food intake of about 350 calories a day for children (about one can of fizzy drink and a small portion of French fries) and 500 calories a day for adults (about one large hamburger),” Swinburn said. “Alternatively, we could achieve similar results by increasing physical activity by about 150 minutes a day of extra walking for children and 110 minutes for adults, but realistically, although a combination of both is needed, the focus would have to be on reducing calorie intake.”

    He emphasized that physical activity should not be ignored as a contributor to reducing obesity and should continue to be promoted because of its many other benefits, but that expectations regarding what can be achieved with exercise need to be lowered and public health policy shifted more toward encouraging people to eat less.

    Catalogue no: T1:RS3.3, oral presentation, Room: Elicium 1, 15.00 hrs CET Friday 8 May.

    Comments

    Exercise, even of the aerobic variety, uses surprisingly little energy.

    Take in more calories than you consume, you gain weight. Take in fewer than you consume, you lose weight.

    Eating too much (of practically anything) makes you fat. What a revelation.

    Hank
    Right, but media exposure has provided a skewed perception of that in the last 15 years or so.   It's been all exercise.   This isn't a scientific number but my experience tells me that people consistently overestimate the calories they are burning doing exercise and underestimate the calories they are eating.
    Strength exercise can indirectly burn calories by stimulating the growth of lean tissue, which will increase one's base metabolism. I think a pound of muscle uses about 70 calories a day just to sustain itself.

    That being said, portion control should be the guiding principle. A distasteful concept for many, unfortunately.

    Stop dieting; keep track of everything that you eat each day. No one wants to be overweight! The most difficult thing to be able to control to keep your weight in check is mindless grazing. It is not always easy to do, but eat to live don’t live to eat. Some type of daily regimen is needed by everyone; but do not diet, your body needs nourishment. Diets and diet aids do not help anyone!
    There's a good chance a significant portion of Americans are fat because they have an iodine deficiency. Iodine is a necessary micronutrient that your body cannot make you have to get it in your diet.
    Common symptoms mimic hypothyroid, and include weight gain on really low caloire diets, cold hands and feet, dry skin, fatigue, and long menses in women. Also, your children can have lower IQ.

    WHO claims that there is no iodine deficiency in the US, but they haven't done the due dilligence in years, they just assume that offering iodized table salt would fix the problem. But 68% of Americans don't eat table salt, because we're rightfully afraid of hypertension. Manufacturers don't put iodized salt in processed foods, so even if you eat 3000 mg of sodium from soda and fast-food you haven't gotten your iodine. They used to use iodine in milk andbread processing, but stopped, so you don't get it there. And green leafy vegetables won't help, because our soil has been depleted. Japanese people get alot of iodine from eating sea-vegetables, but most Americans wouldn't touch whole seaweed with a ten foot pole. Some seafood has iodine, depending on where it came from, and how well it adsorbed the nutrient, but unless you eat a lot of seafood consistantly, which is expensive, there is a good chance you are iodine deficient. At least one study showed that in the mid 90's, 11% of Americans were difficient. That's more then 1/10, and we're probably higher then that by now.

    if you are a fat American, with hyperthyroid tendancies, and especially if you have a TSH that is high, you could be iodine deficient. Get a supplement of kale, eat some seaweed, replace all your salt intake with iodized salt. I did, and I felt immediatly better.