Just like in your experience, the weight gain made me less energetic, so I had to start exercise from a very low point. I really cannot emphasize enough how out-of-shape I was at that point, and I hope that others, who may feel they are too weak or fatigued to exercise, can use my experience as motivation.
It probably took me three months of gradual improvement before I started to notice real physical changes. In order to burn many calories–and really target that belly fat–you need to be able to do cardio for at least 30 minutes. But it’s important to work up to that level very slowly to avoid injury and burn-out. My own suggestion would be to start walking five times a week, for short distances, then increase the distance until you’re able to walk three miles each workout at a 15 minutes/mile pace (for a total of 45 minutes). Then I’d add short running intervals each week, as short as a minute at a time, and keep increasing the intervals, while walking less, until you can run the full three miles. That could take several months, but it is well worth it. At that point, you can think about increasing mileage, but it isn’t necessary. My own goal is to add one total mile a week until, in half a year, I’ll be running 40 miles a week. That’s my ultimate goal: 8 miles, 5x a week. Occasionally, I’ll do a “fast” run, but usually I keep my pace slow enough that I never have to breathe out of my mouth, because that ensures I go slow enough that I won’t overtrain.
Low-carb is by far the worst diet for most people, and low-fat is much better. However, I’ve become “macro-nutrient agnostic,” which means that I’ll eat as much fat and carbs as I want, as long as I remain within my calorie goals, which I set at 500-1000 calories below my BMR of 2,500 (if your BMR is lower, I would aim for a smaller deficit, like 400-600). On the days that I run, I increase my calorie allotment, and currently that means an additional 500 calories five days a week. Sometimes I’ll have a cheat day, like if I go out with friends for dinner, but I’ll make sure I don’t exceed my BMR+exercise.
I like sugar, so I have some sugary food each day–or more likely sugary drinks. They can increase calories rapidly, but I’m careful to add them to my total. I prefer to eat a little more sugar, and a little less fat, but that’s just personal preference. And because fat is so calorie dense, I can have a whole can of soda for the “price” of about a tablespoon of olive oil.
The only macro-nutrient that I consider non-negotiable is protein. I aim for 100-150 grams a day. If I eat less, I don’t recover from exercise as well. If I eat more, my digestion suffers. My protein intake is probably higher than yours would need to be, because I’m also lifting weights 4x a week, and so I need the extra to build muscle. If you don’t lift weights or do resistance training, your protein needs will be a little lower.
Weight-lifting will also slow your weight loss, but in a good way. I weigh 195 pounds now, which is only 20 pounds less than my max, but my belly looks significantly smaller because I’ve also built several pounds of muscle.
