If you are trying to lose 100 pounds, beyond diet and exercise you may need to examine other areas of your life to understand how best to achieve weight loss.
People who have 100 pounds or more to lose know all about what they should be doing to lose weight, says Gail Curtis, assistant professor at Wake Forest University, Winston-Salem, NC. In addition to nutrition and exercise, Curtis says it is important to consider stress, your sense of fulfillment, your work and home environment, and even people in your life who may be sabotaging your best diet efforts. Then you can concentrate on developing and sticking to a weight-loss plan.
How to Lose 100 Pounds: It Starts With Counting Calories
Counting calories is going to be a part of this process. Here are guidelines to follow:
  • If you want to lose a pound a week, you have to cut out 3,500 calories, or roughly 500 calories a day.
  • You never want to eat fewer than 1,200 calories a day, “and that’s on the low end,” says Curtis. You can always increase your physical activity, however.
  • You can safely aim to lose 1 percent of your body weight per week; a woman weighing 250 pounds should aim for a 2.5-pound loss per week, eating about 1,250 calories less per day.
  • Counting calories involves not just the food you eat, but also the calories you burn through exercise.
  • Keep a journal of what you ate, how much you exercised, and your thoughts and feelings at those times, and limit yourself to one weekly weigh-in to avoid focusing too much on the scale.
Good nutrition is key, says Curtis. Many people who want to lose 100 pounds are used to eating foods that are high in calories and low in nutrition. The challenge is to practice the reverse: Learn to eat the correct portions of foods that are low in calories but high in nutrition, such as fruits, vegetables, whole grains, and low-fat dairy.
How to Lose 100 Pounds: Break It Down Into Stages 
How long it will take to lose 100 pounds varies — a 250-pound woman might need 40 weeks or more to achieve her goal — but Curtis recommends that you develop weekly and monthly goals that will help you track your progress and avoid becoming overwhelmed or discouraged. Attainable, feel-good goals include: 
 
  • Being able to get down on the floor and play with your children or grandchildren
  • Being able to walk around the mall without feeling short of breath
  • Being able to do 20 minutes of physical activity three days a week — mornings are best, says Curtis (and work up to 30 minutes most days of the week)
  • Eating four servings of fruit or veggies every day of the week
  • Eating a healthy breakfast every day that includes a low-fat protein
How to Lose 100 Pounds: Exercise Is Non-Negotiable
Being physically active is an essential part of losing 100 pounds. “This was the biggest challenge for our clients,” says Curtis. “They would say they couldn’t do it because of their ankle or their back pain. But everybody can do an exercise program.”
Curtis recommends:
  • If you have a lot of joint pain, start with chair or water-based exercises.
  • Try walking short distances and gradually building up your endurance.
  • Involve a physical trainer or an exercise buddy as you get moving again.
How to Lose 100 Pounds: The Aftermath
Many people worry about how their body will look once they lose 100 pounds. This “depends on your age and condition of the skin,” says Curtis. “Some people’s skin will retract. For some it will not.” Once you reach your goal, if you find that sagging skin bothers you, you might want to investigate cosmetic surgery to remove excess skin.
Of course, the health and fitness advantages of losing 100 pounds, plus how much better you will look and feel in clothes, will more than make up for any after-effects of your overweight. With determination and a few smart diet strategies, you can achieve your goal.