I have tried to lose weight.  Why is it so difficult?

Metabolic studies show that, barring any major endocrine disorder, a person getting 20 minutes of moderate exercise (defined as waling at a moderate pace) 4 - 5 times per week will require 10 calories per day to maintain each pound of weight.  As an example, a 200 pound who does not have endocrine problems and who does get the moderate level of exercise will require 2000 calories per day to keep his weight at 200 pounds.  If, however, the person has an orthopedic problem and can't get this amount of exercise, the maintenance  calorie intake may be only 9 or even 8.5 calories per day per pound.  The number that most people do not know is that it takes a cumulative deficit of 3500 calories to lose 1 pound.  If that 200 pound man needs 2000 calories per day to stay at 200 pounds and if he eats only 1500 calories per day, that is a 500 calorie daily deficit and it will take him 7 days to lose 1 pound if he stays on that diet.  By the same token, if he can only cut his diet to 1700 calories per day, his calorie deficit will be only 300 calories and it will take him 12 days to lose that pound.

Diets often fail because people become discouraged after the initial rate of weight loss slows down.  If a person is able to go on a calorie restricted diet and follow it fairly religiously, it becomes apparent after a few weeks that weight loss is not linear.  That means that a graph of weight versus time will not follow a downward sloping straight line; the line seems to level off, and weight loss slows or stops.  The person notices that the diet that he or she is using follows a law of diminishing returns after two or three weeks.  For many people, not understanding why this happens leads to discouragement and abandonment of the diet.  I have heard many people say to me that "diets don't work for me; I lose a few pounds at first, the weight loss stops, and then I gain it all back."

The answer to the riddle of the diminishing returns feature of weight loss while dieting is straight forward.  If you are given a diet with a specific calorie content, eventually, your weight will come down to the level that is supported by the daily calories in the diet.  If the 200 pound man described above loses 10 pound and now weighs 190 pounds, he will only need 1900 calories to maintain that weight and a 1700 calorie diet will only create a 200 calorie daily deficit; continuing on the 1700 calorie diet will take 18 days for him to lose the next pound.  If the man gets down to 180 pounds, the 1700 calorie diet will only provide a 100 calorie daily deficit; in this situation, it will take the man five weeks to lose the next pound.  The point here is that, after the initial weight comes off comparatively quickly with a diet of restricted calories, the man needs to reduce his calorie intake further to maintain the daily calorie deficit and continue a steady rate of weight loss.  He might start out with a 1700 calorie diet, but in two weeks, it should be lowered to 1600.  After a month, he should cut out more calories and continue to lower his calorie intake every two weeks until he reaches his desired weight.  Very few dieters understand the need to keep reducing calorie intake after the initial weight comes off because this fact is usually not explained to them.