Exercise makes you feel hungry. If you feed after an exercise you will eat enough to balance out the calories that you burnt. There is a thing called homeostasis. It tends to keep the body composition stable. The homeostasis is based on a n...umber hormones that work together to keep body composition in balance. We will look at the homeostasis mechanisms in the diet myth article.
So yes you will need to couple the exercise with a diet to reduce weight, otherwise you will always compensate in your diet.
If you are required to diet anyway, then what is the point of doing exercise. Exercise helps in the following ways for priming the body to lose fat instead of muscles.
1) While you are dieting to lose weight, you will lose muscle as well. Muscles are a very important part of our body, losing them is not good. Exercise tells the body that those muscles are required and it should keep them around. Exercise helps keep the muscle loss to a minimum.
2) Exercise can also help by keeping the metabolic rate higher, and there by increasing fat burn rate. You don't need to burn much fat during the exercise, although exercise will do so, but increasing metabolic rate helps burn fat all day long.
3) Exercise also helps in hormonal balance. There are several hormones that help burn fat, the most important of them is the testosterone, the hormone that also builds muscle. Women also have small amounts of testosterone, and exercise will also help them burn fat.
4) Exercise also helps in reducing glycogen storage in muscles. This helps in reducing insulin resistance. Allowing the insulin levels to go lower faster and helps in increasing fat loss.
Not all exercises are created equal. Some exercises aid fat loss more than others. Weight training and High Intensity Interval Training (HIIT) helps more than aerobic exercises.
1) Multi-functional Weight training and HIIT, help exercise all muscles of the body, preserving them. Aerobic exercises like running generally, exercise only a few muscles.
2) Wight training is the best for building muscles for increasing the metabolic rate. HIIT follows closely. Aerobic exercises do not help build muscles.
3) HIIT is known to be the most effective in increasing testosterone. Weight training follows very closely. Aerobic exercises generally do not help in this regard.
4) Glycogen stores are for emergency energy requirement. Oxygen is used for burning fat to supply energy in the normal case. Glycogen is used when the muscles require to generate energy faster than blood can supply oxygen. In this case glycogen is burnt anaerobically to produce energy. This is by definition an anaerobic activity, and aerobic exercises cannot help here. HIIT is the best in this regard as it tends to maximize the Oxygen requirement, because of exceeding it.
Believe it or not, exercise does have negative consequences if not done properly.
Exercise causes wear and tear of muscles ligaments, etc. There must be enough spacing in the exercise to recuperate. Do not over do exercise. There are terms for too much exercise, chronic cardio for people who do too much aerobic exercise, and overtraining for people who do HIIT and Weight Training. Weight Training/HIIT generally requires a minimum of 48 hours break.
Aerobic exercises should also involve breaks depending on the length and effort in the exercise. Take at least a week off after a half marathon, and don't do full marathons more than once a month. Generally you do not want to run more than half an hour everyday, and not more than 3, 1 hour runs a week.
The most important indicator for chronic cardio and over training is lack of appetite and all day feeling of tiredness.
Avoid weight machines that provide balancing automatically. This causes the balancing muscles to be underdeveloped compared to the main muscles, and can cause accidents if you try to use your full muscle power in real life situation. It is best to use a bar-bell and dumb bell. To get the most benefit of weight training, use compound lifts instead of isolation movements. Isolation movements require machines and exercise very few muscles, which is inefficient.
To sum it up.
Exercise in isolation does not help in weight loss. Dieting in isolation can help in weight loss. Weight training and HIIT are the best ways to increase your fat loss, and resist muscle loss. Be careful how you exercise.