There's one simple rule – to lose weight: you need to consume fewer calories than you burn. Also, when you want to gain weight you need to eat more calories than you burn, and if you just want to maintain your current weight, calories in should equal calories out. Although you still need to watch your protein, carbs and fat ratio and carefully choose your carbs, counting calories is a big help on your weight loss journey. A calorie deficit is the key, but make sure you eat at least 1,500 calories per day – most of the calories you consume are spent to keep you alive and healthy and a significant deficit will lead to serious health issues. The average recommended daily calorie intake is 2,700 for men and 2,200 for women. Roughly speaking if you burn 500 more calories than you eat every day, you can lose about 1-2 pounds in a week. There's a variety of online calculators that can help you carefully track your calories and determine your deficit.