People can make all the excuses they want for being overweight. Physiology is only a small part of it. What percentage of people were overweight/obese 40 years ago as opposed to today? Do genetics change that much in 40 years where 70% of the AMERICAN population suddenly has the "fat, malfunctioning thyroid gene"? I think not. I'm not "fat shaming" anybody. I just think it is selfish and unfair for the fit/healthy people to have to pay higher medical premiums as a result of all the health issues from the 70%(which, in most cases, is preventable).
I dropped 50 pounds about two years ago. Do I still eat junk food? Yes. Do I still drink alcohol? Yes. What's different? I started exercising, cut out the soda and cut back on the alcohol and junk food. Everything in moderation.
I think it's very complicated, and there are a lot of reasons why people are fat today compared to 40 years ago. Which is why we can't just say "I did it, so can you!" Like the exercise thing. I like to say "you can't exercise your way out of a bad diet". Or, most people can, to a certain age. For me, it was about 24. I know people who could just "exercise more to eat whatever they want" until 30, 40, 50, 60, depending on genetics and joints (i.e., the runners could do it longer, but not everyone has the physical ability to run).
Look at WHAT we eat now - more processed foods, more junk food, more sugar, more soda.
Look at how little general movement we get. I mean, have you seen how the Amish eat? But they are physically active in their daily lives.
My dad was an auto mechanic, and worked on his feet most of the day.
My mom SAH and was a bank teller. At home, she did housework, hung laundry to dry, gardened - was physically active (but still overweight except for the years from 38 to 42 when she started walking 3-6 miles a day and went on a 1000 cal a day diet).
Most people I know have sedentary jobs (myself included), and work longer hours than our parents did. Less time to be physically active and less time to actually cook.
And of course, the prevalence of junk food and fast food has gone WAY up. It's just so much easier to pick something up.
Add to that stress (economic and other) that affects your weight.
Plus now we are learning more about overweight - how your gut flora affects your health and body - more C-sections, less breastfeeding = more health issues. Your body makes more fat cells as a child or teen - so more fat teens = more fat adults. A fat adult who was fat as a teen simply has more fat cells and won't be able to maintain the same weight as someone who has never been fat. Plus, having been obese changes how your body processes food, particularly sugar and starch. This is why someone who has never been overweight can eat a certain way, but someone who has been fat and lost weight cannot eat the same way (or they will gain weight back).
It's all pretty fascinating stuff.
We cannot boil it all down to one thing. The answer is not going to be easy or simple.
My old company has new health insurance policies - you have to go through tests for BMI, blood sugar, weight, smoking, and blood pressure. If you or your spouse fails 3/5, then your insurance premiums are higher. I think this is actually a pretty good idea. I wouldn't want it to be a single measure affecting your premiums, but several risk factors? Why not.