Eating healthy and working out is good for a body, to a point. You put in what you put out. That being said, there is difference between an individual’s metabolism, based on age, current weight, hereditary and lifestyle factors; some people have naturally fast metabolisms, and others, slower.

People who are overweight actually tend to have fast, though very inefficient metabolisms. It takes a lot of energy to maintain large amounts of ANY bodily tissue, whether it’s fat or muscle. Oxygenated blood and nutrients need to be sent to each cell. This is why overweight people who initially diet lose weight pretty rapidly, if they’re doing it right; people who have a lot of muscle mass need to eat a lot to maintain it, but their cardiac output is far more efficient than a couch potato.

Slow metabolisms occur in relatively few members of the population. If you are heavier with a slow metabolism, heavy cardio will alter your metabolism, but as soon as you stop, your metabolic rate would gradually return to levels they once were. Slow metabolisms, over the long run, are far more efficient than faster metabolisms- you put in much less energy, and expend only moderate amounts of energy. The longest living animals tend to be those with slow, efficient metabolisms.

I have a naturally slow metabolism, and have lost weight by limiting my caloric intake to around 1000-1200 a day, and walking long distances with moderate speed. I initially tried working out a lot, but that made me pretty hungry, and more likely to overeat. I spent years eating about 2500+ calories a day, and not getting off the couch. Now, if I eat over 1200 a day, I feel tired and shitty. I have never had this much energy before in my life. I’ve lost almost 70 pounds, and it’s been so easy when you get the formula right.

TL;DR Weight is easy to drop off if you know how to work your body in the right way.