I have trouble imagining that it would be better. Look at people who come into access with large sums of money for reasons outside primarily mental achievement - athletes after leaving pro sports, musicians after they stop performing, actors after they stop acting, lottery winners, and so on. Some quick searching turned up articles like this [1]:
"The researchers found that the athletes' weight held steady for over 100 years, with the majority of them weighing in at what is considered "normal," -- i.e., with a body mass index (BMI) between 18.5 and 24.9. However, around 1991 the average player's BMI began to rise, and over the last 25 years nearly 80 percent of players fall into the overweight or obese category with a BMI above 25. "
There's a strong correlation between socioeconomic status and obesity, but that doesn't mean it's causal. Obesity is primarily driven by a lack of impulse control. If you force yourself not to over-eat, you could live off of even McDonalds without becoming obese.
[1] - https://www.sciencedaily.com/releases/2016/09/160930085937.h...
Here is a link to the actual paper [1]. Their concluding statement was:
"Professional athletes are not immune from the growing obesity crisis and may not provide optimal role models of health. Concussions have drawn attention to overlooked long-term health consequences of sport participation. Increasing body mass in professional baseball players warrants similar attention for its potential impact on long-term morbidity and mortality because these players hold a special place as role models of health and human performance in our society."
Now, there are lots of big boys in the NFL that definitely have a couple extra pounds on them, which could also be skewing numbers.
Obesity is driven by systemic commercialization and sugaring of our food supply, combined with inequality of too low a pay, too many hours, to little vacation. Even funding of highway and road infrastructure over other areas is a contributor here.
Another large part of it is because we elect to keep both private health insurance policy which ends up being racially and economically biased, and what little social safety we provide is riddled with self-imposed rules of means testing and other red tape cutting the effectiveness of even the meager allocation of resources. Many very easily and economically preventable illnesses and deaths keep happening and that is a decline to me. e.g. https://www.propublica.org/article/black-diabetics-lose-limb...