How could a person who is 75-100 pounds overweight and sedentary lose weight?

Obesity: Lowered calorie but adequate diet and get up and move as much as possible, walking an hour a day a good start, work up to it.

Get less sedentary !: Eat healthfully. Try to eat at least 5 servings of vegetables & 4 of fruit per day. Increase nutritional fiber. Avoid refined sugar & junk carbohydrates. Avoid alcohol, sweetened juices, soda & caffeinated beverages. Aim for 7.5 to 8 hrs of sleep / night. Hydrate w at least 64 oz of water / day. Calories burned must > calories consumed. Do both cardio & weight training.