Whether you want to lose weight or maintain your current size, weight management comes down to a simple equation of calories in versus calories out. You don't have to spend money on a specialized diet program. Simply monitor the number of calories you eat and balance it against the calories you burn through physical activity.
Calculate the number of calories needed to support your lifestyle. For a basic estimate, multiply your weight by 15. For instance, a 150-pound person would need roughly 2,250 calories per day. This formula, designed by Harvard Medical School, assumes that you exercise for at least 30 minutes a day.
Read food labels. The U.S. Food and Drug Administration requires manufacturers to print nutrition facts on the backs of food packages. At the top of the label is information about serving size and calories. For instance, if you read that there are 150 calories per serving of cookies, but there are two servings in a package, then you would be eating 300 calories if you finished the entire bag.
Keep a food journal. Write down everything you eat from the omelet at breakfast to the mindless spoonful of peanut butter in the evening. At the end of the day, add up the number of calories you've eaten using information from food packaging and from an online nutrition database such as Livestrong.com's MyPlate. Monitor your food intake for one week without making any changes to your diet.
Review the journal. Flip through the week's worth of data and look for trends. Do most of your calories come from meals or snacks? Do you eat breakfast or do you overeat in the afternoon and evening? Based on what you've learned, set small goals for the coming week. For instance, you might try to eat three 300- to 500-calorie meals and two 100- to 200-calorie snacks each day instead of binge eating in the evening.
Determine your caloric expenditure. The amount of energy you expend during exercise depends on your weight. For instance, a 160-pound person burns roughly 438 calories in an hour of hiking, while a 240-pound individual burns 654 calories doing the same activity, according to MayoClinic.com.