I bike 20 to 40 miles a day. Never just to be exercising, but always to get somewhere. I have never owned a car. Unless it's made impossible, I always take stairs rather than elevators or escalators, even in 40 story buildings.
I eat cereal, fresh raw fruit, and fresh raw vegetables, and that's it.
I do eat other foods occasionally, if someone else is serving them to me. But I never choose them or buy them.
I consume the cereal without milk, right out of the box. It's cheap, convenient, filling, and nutritious. It has a long shelf life. There's no cooking or other preparation, no need for silverware or dishes, and no cleanup. I choose the brands which have no added salt, sugar, added nutrients, or other additives. I choose both the cereals which are intended to be eaten cold in a bowl with milk, and cereals that are intended to be boiled in water.
I prefer my fruit and my vegetables fresh and raw. That way they have more flavor, more texture, and more nutrition. I don't add any butter, margarine, cheese, oil, salad dressing, salt, or anything else. Since I shop by bike, I buy small quantities frequently. (That way I don't need to refrigerate anything, and thus save the cost of electricity that would be needed to run the refrigerator.)
I eat when hungry, and I eat until I am full. I don't limit calories. I find that I typically get anywhere between 1000 and 3000 calories, 50 to 150 grams of fiber, and 2 to 20 grams of fat per day
My health was excellent when I was fat, remained excellent while I was losing weight, and is still excellent. I haven't been sick since I was a small child, not even with a cold or headache. I haven't been to a doctor or dentist in over a quarter century, other than two quick trips to the ER for minor accidents, and eye doctors for getting new glasses. I did not seek medical help, or join any group or plan, or take any drugs, or undergo any surgery, for losing weight.
I'm skeptical of the frequently quoted statistic that 95% of all people who lose weight soon regain it.