Consume less calories than you expend, and you will lose weight.
Now, that’s easier said than done. I know, since I’ve never been anywhere close to “normal” weight (not morbidly obese, just in the overweight-to-slightly obese category). So, to implement the Conservation of Energy Diet for myself, I used WeightWatchers (online–no meetings). My doctor advised it as the most sensible, non-faddish, long-lastingly successful plan he knew about.
The whole thing is about portion control. You can eat whatever you want (your body gets energy from any food), but you have to keep track of “point” values. Generally speaking, points are just scaled calories (about 50 calories/point, give or take). It’s easier to keep track of small numbers than big ones.
For reference, I am about 6 feet tall, male and 42 years old. On WW, I am allocated 26 points/day, plus 35 “discretionary” points for the week. That amounts to an average of roughly 1500 kcal/day, which should translate to 1-2 pounds of weight loss per week. That means that I must be at a maintenance level of consumption at 2000-2500 kcal/day. Doesn’t really matter what I eat, as long as I keep to those amounts.
Now, my problem has always been portion control, and I can pack away a lot of food. On WW, you quickly learn that carbohydrate rich foods like spaghetti and candy add up to a hell of a lot of calories with little or no stomach-filling bulk. If I want to fill up and not use up my points, I must eat a lot of veggies and lean proteins. A cup of carrots is zero points, a cup of beans (cooked) is about 2 points, and a cup of pasta (cooked or 2 oz dry) is 4 points. So, how much pasta can I afford to eat and still lose weight? Not very much. But I can go crazy once in a while with my discretionary allotment. A “small” piece of cake might be 4 points, or I’ll have 2 oz of ice cream instead of 8. And I’ll walk a little extra and get point credit for exercise.
AFAICT, Atkins and South Beach effectively just do the same thing by restricting calories as a by-product of getting rid of calorie-dense (but not particularly filling) foods.
It’s all about energy balance (and changing habits).
Rick (down about 10 kilograms so far, and keeping it off)