One reason is the pious-sneer diet. First, you get hounded that you need to lose weight. Then, you are stuck eating fast, good-tasting poison 5 or more times per week to keep your time going. They also discourage steady walking to help you lose weight or, at least, be "fit and fat" at the same time (this is when you are physically active but still are too fat, and with few or no health effects from the fat). You sit in a car all day driving or riding, or at a study. And, each time you try cutting a few calories, something comes up where you "need" to eat (usually at lunch).
I have also found that the jokehovians are against doing anything that might improve themselves. "Wait on joke-hova" is the standard answer. Do they take vitamins? Remember, around 90% of Americans need more magnesium in their diets, and a good magnesium supplement might help a bit. But no, they hate when someone knows about which vitamin, mineral, or herb would help people to be just a bit less sick. Instead, it is prayer and studying that stupidity book (the LIE-ble) along with washtowel littera-trash. How much can you raise your metabolism by praying to a bunch of reptilians that laugh at you with each extra pound of lard you gain?
Another thing is they are against fun. What happens when many people are bored? They eat. What happens when you eat because you are bored? In time, you get fat. Field circus does not alleviate the boredom--it aggravates it. You don't get to play video games, listen to real music, watch good videos, or play real games or read good books. Even going on vacation requires attendance at all boasting sessions and all field circus attendance. Do you wish to go from New York City to a country like Germany or New Zealand just so you can waste the whole thing on field circus? No fun there--so, boredom eating continues. Throw in sleep deprivation, and that is a recipe for, not only more eating, but making your metabolism even worse.