Why is it scientists can't get an accurate grasp on the calorie content of foods, and how our bodies process them?
I just posted another article that talks about the difficulty of doing human nutrition studies. Way back in the 1970s, I saw a television news magazine report about a group of nutrition researchers who found human volunteer subjects who were willing to be shut away from their normal life for weeks (months?) at a time (being paid for their time, as I recall) in conditions under which EVERYTHING the subjects ate was weighed to the nearest gram. The TV report even showed researchers washing crumbs off plates with distilled water so that the subjects ate every morsel of their measured meals. That was part of a study designed to elicit new information about human nutrition. Alas, I've never heard of results of that study. (Probably, the sample size was too small to have adequate statistical power to reach any firm conclusions.) This will always be the problem with human nutrition studies: people think they remember how much they eat, but often enough they don't really remember in detail, and the usual study methodology for a nutrition study is to rely on subject self-reports. If the sample size is extremely large, sometimes there is enough statistical power to pick up a few tantalizing signals from masses of carefully gathered data, but then there is still the whole issue of how well actual human beings apply advice based on the studies that have been done to date.
I am amazed at how much day-by-day obesity in very young people I now see in my town. I never imagined that most Americas in my generation or the younger generation would be as bulky as they now are. And the United States isn't even at the top of the world league tables in obesity. People all around the world today have eating tendencies based on human beings evolving in conditions of food scarcity, but there are fewer and fewer places each decade that still suffer from food scarcity. (Ethiopia is still poor, but it is now a food-exporting country.) The challenge for humankind in the remaining years of my life will be learning how to do what is "unnatural" and eat less than what is readily available to eat.
"And the United States isn't even at the top of the world league tables in obesity."
True, but only just (according to the WHO). The only countries that beat it on overweight or obese percentages of population are Saudi Arabia, Panama, or have a population under one million.
Perhaps they can but until science can unlock the psychological interaction of people and food they're not going to change anyone's food habits.
If you look at the progress of medicine with respect to addictive behaviors, there seems to be very little progress. I believe food eating behaviors are very similar. In fact I think obesity is the hardest addiction to overcome simply because you can't eliminate food from your diet as you can eliminate all other addictive substances.
I know I've lost 30-40% of my weight several times and kept it off for a number of years but it always returns due to my inability to resist the psychological pressure to over eat and/or eat dense caloric foods.
It seems to me that the effect of food on the body has been studied for at least 50 years.
No matter how complicated it is, shouldn't there be a few basic things everyone can agree on? It seems that each new diet (based on scientific principles) contradicts the last. Low fat, low carb, low calorie, vegan, no dairy, no wheat...
They can't even agree on whether a calorie matters. (i.e. is eating 100 calories of steak vs eating 100 calories of sugar the same?)
Why is it scientists can't get an accurate grasp on the calorie content of foods, and how our bodies process them?