With a healthy plan, how much weight can you really expect to lose in 30 days? Following a strict plan, you can anticipate losing 8-10 pounds per month or 2 pounds per week. One pound of body fat equals 3,500 calories, so that means burning/cutting 1,000 calories per day. As for the gym, here are a few general examples of calorie burn based on a person who weighs 150 pounds. Treadmill running for 20 minutes at 6 mph: 229 calories Elliptical for 30 minutes: 179 calories Swimming breast stroke for 30 minutes: 189 calories Kickboxing for 30 minutes: 357 calories The American Academy of Nutrition and Dietetics recommends that women never eat less than 1,200 calories per day. Under that, and you're messing with your mental and physical wellness.