But you cannot depend on 30 minutes of running to help you solve the calories/weight problem.

You can very easily eat more calories in 10 minutes then you can burn in 30, at least I can and many, many other people can.

You have to look at calories into your body if you are concerned about weight. While exercise is good, it is certainly not a magic bullet. And the effects of overdoing exercise are not too good. (Arthritis, back problems — I had a disk taken out — knee problems, etc.) Exercise is good — perhaps necessary in most circumstances — but you should also look at the calories in part of the equation.

Anyway, good luck! If you are substantially overweight, you probably have to reduce the amount of calories in, as much as I hate to say it. The logic of this is inescapable.

I wish it weren’t the case…

until I made a sensible eating plan for myself including whole foods and sensible portions, I was never able to keep weight off. This also included doing some form activity I would enjoy most days of the week.

I’ve lost 150lbs and kept it off for over a year now. I’ve kept over 125 of it off for over 5 years. those last 25lbs can be a beast to lose.

I stick with veggies, whole grains, and proteins, for the most part. I don’t restrict my intake. I’m not actively seeking to lose at the moment (building strength/mass).

You can’t ignore reality. you don’t have to deprive yourself, however. Sensible, moderate adjustments have worked best for me.

I was able to lose 50 pounds by eating smaller portions, and walking 5 days a week for about an hour.

The answer is.. give it a try for a couple of weeks and see what happens. If it works for you then you’re good to go. If it doesn’t you’ll have to adjust SOMETHING — either what (or how much) you eat, or what you do (and how often) for exercise.

Yes, you can, say, do physical activity for 12 hours a day and lose 30-40 pounds over the course of 3-6 months. Ocean-crossing rowers prove this regularly.

A lot of that lost mass is muscle. And it’s not the sort of program that fits in well with a modern lifestyle including such activities as working, social interaction, sleeping, and taking care of life’s sundry tasks.

I’ve at various times of my life spent 3-4 hours a day in a pool, or on the road cycling. I ate a lot. I was in good shape. My body fat never fell much below 10-12%. Turns out that being that physically active actually is detrimental to some fitness goals such as building strength and muscle mass — excessive cardio is catabolic (muscle wasting).

The reality is that for virtually all athletes, bodybuilders, strength trainers, and other highly active individuals, do pay close attention to their diet. I’ve increasingly done so over the past three years as I’ve entered my 40s and taken strength training far more seriously.

So sure: I don’t “count calories”. I do keep pretty close tabs on what I am eating, more specifically quality of foods (emphasizing protein and veggies, minimizing processed carbs).

And yes, individuals differ. While I’d agree that there are many people on “fitness programs” who fail to press themselves with sufficient intensity, there are also those who face serious obstacles.

dietdingbat’s answer was far superior to yours. It depends.