The U.S. adult population in the 1970s ate an average of 2400 calories a day. By the 2000s, our calories were up to 2900.
Putting a face on the statistics
What did average adult weight do as we increased daily calories by 500? It increased by 8.6 kg, from 72.2 to 80.6 kg. In U.S. units, that’s a 19 lb gain, from 159 to 178 lb.
Children increased their average intake by 350 cals/day over the same time frame.
If I recall correctly, I’ve seen other research suggesting the daily calorie consumption increase has been more like 150 to 350 per day (lower end for women, higher for men).
Details are in the American Journal of Clinical Nutrition.
The study authors don’t say for sure why we’re eating more, but offhand mention an “obesogenic food environment.” They don’t think decreased physical activity is the cause of our weight gain; we’re fatter because we eat too much.
h/t Ivor Goodbody
Worth saying this is disputed but…simple explanation of obesity epidemic may be we eat 500 cals more than in 1970s http://t.co/k3RQnIdCGn
— Ivor Goodbody (@IvorGoodbody) May 22, 2014
Diabetic Mediterranean Diet 
Simple explanation: we eat more because we are getting fatter. And we are getting fatter because we eat too much grains.
The idea that we are eating more because we are getting fatter is a key point for Gary Taubes.
Why didn’t you ask: “Would you eat more calories if you were getting fatter?” Are you aware of the causality problem within your question?
Saying that we are fat because we eat too much is not derived from physics’ laws.
Energy Intake = muscle increase +body fat increase + energy expenditure
Why don’t I create more muscle if I eat ” too much”? Why don’t we talk about gluttony and sloth when someone increases his/her muscle mass? Aren’t they eating more than they burn? Probably. But in this case nobody says they are glutonous and lazy? Why? Where in the thermodynamics’ laws is the difference between getting fatter and increasing your muscle mass?
I am not putting words in your mouth. I just try to explain that the energy balance view of obesity is flawed and useless. I suppose Taubes’ opinion would agree with me, but I can’t know.
When I started a low carb diet, I simply wasn’t very hungry. I found that my caloric intake had dropped into about the 900 to 1000 k/cal per day range. My TSH rose and my weight loss stalled for a few months. Simply bringing my calories back up to about 1500 or 1600 per day got my weight moving down again and brought my TSH back in a normal range (my HMO won’t do a complete thyroid panel, so I can’t say what else was going on with the thyroid).
I get that with prolonged starvation I’d eventually have started losing weight at that low calorie range. But adding 500 or 600 calories actually helped my weight loss.
Calories certainly count, but I don’t think the obesity epidemic is at all as simple as 500 more calories a day.
Jan, I appreciate your input.
Increase the time spent without eating: call it intermittent fasting if you want to, but simply wait AT LEAST 12 hours between eating dinner (including any late night snacks…) and “break fast.”
The issue is that digestion requires specific requirements of, and imposes various costs on, your body, and your body needs (time) to recover from that.
This works well UNLESS you have already killed off all of your insulin producing cells, at which point I imagine the outcome is less certain.
The idea is to avoid prolonged starvation. But from an evolutionary perspective, enormous amounts of food were simply not readily available at any time of the day or night. And the human body is not meant to be in a constant state of dealing with elevated amounts of sugar, etc. People are omnivores, but potato chips and ice cream were not readily available in the evening in any ancestral diet.
Richard, I like your ideas. The potential health-producing mechanism is called hormesis. The idea that we’re designed to eat every 3-4 hours is nuts. Any readers taking drugs that could cause hypoglycemia need to check with their healthcare professionals before making any drastic diet changes, including skipping meals.
Here is my case study, fyi:
In 5/2012, started LCHF eating about 1500-1600 calories/day. Weight was 175 lbs at 5’11” but with small belly.
In 7/2013, continued but added 2X/week of 40 min of High Intensity Resistance Training. Still eating about 1500-1600 calories/day of LCHF but weight was 156 lbs. No other exercise + fairly sedentary otherwise.
Now, I need to eat 2200-2300 cal/day just to maintain my 156 lbs.
BTW, I am over 70 yrs old + take no meds.
So had to increase my calories of LCHF to maintain my weight.
My take: it’s not just about calories.
Evinx, thanks for sharing! Bill Lagokos talks about the calorie issue at his blog.