A lot of the answers you will see here will tell you to buy some sort of supplement. Don't take diet pills. They are unnatural and dangerous. It is not the lack of pills that get us heavy; that is not the fix we need. It was (most likely) improper diet and lifestyle that got you the extra weight. That is the fix we need.
The best way to be healthy is through the principles of balance and moderation. You need to eat good food and eat enough of it.
When trying to lose weight, shoot to lose 1-3 pounds per week. No more. Don't go hungry, just keep yourself filled with good, natural foods.
Don't worry about calories. Caloric science is flawed for several reasons. 1) it assumes 100% absorption, but we all absorb and excrete different amounts; 2) It assumes all calories are processed the same, but calories from natural sources are burned more slowly and evenly than from refined sources; 3) It assumes that the amount of energy released by combustion (burning) in a lab is the same amount of energy released when the food is broken down enzymatically in the gut; 4) It assumes that the same exercise done by different people will burn the same amount of exercise, but different exercises will be harder or easier for different people; 5) People in China consume 25-40% more calories; even the sedentary office workers have more calories and less obesity than we.
Asian cultures have long ago figured out how we should be eating, Ever since we have looked to science to tell us how to eat we have seen more obesity and diet-related disease. If we eat like the Asians, we will look like the Asians. This doesn't mean you have to eat Asian food, just adhere to the principles that are common to the different cultures and cuisines.
You should eat mostly vegetables, mostly cooked (cold and raw foods slow your metabolism because they need to be cooked in your stomach) and a wide variety, mostly fresh and in-season and local, simple grains (more rice, less bread), some fruit, a little meat, no dairy (it's for infants and grows tissue), and no artificial foods.
Avoid artificial foods, including sugar substitutes. Don't worry about calories, fat, protein, carbs, nor any one component of food.
There are several books that explain this strategy of eating. "The Asian Diet: simple secrets for eating right, losing weight, and being well" by Bussell explains the diet and its rationale. "The Asian Diet: get slim and stay slim the Asian way" by Tran has recipes that adhere to the principles. "The China Study" by Campbell has the science behind the recommendation.
Get some exercise every day, but not too much and not always the same exercise. Start slow and work your way up. Calisthenics are great, as is Tai Chi. Walking and swimming are also great. All other exercises should be in a wide rotation.
Follow the principles of balance and moderation and you'll be fine. Most diets in America are not balanced nor moderate.
Source(s):
http://www.theasiandiet.com
http://www.thechinastudy.com