PT on the Net Research

Carb Intake With Weight Loss


I have a female client who is 25 years old and weighs 138 pounds. I calculated her total caloric needs to be 1,969 calories day (this includes daily living calories as well as resting) This client would like to lose 13 pounds. I have provided her with a calorie reduced eating plan of 1,400 calories: five servings of grains, eight servings of fruits and veggies, two servings of milk products, two servings of meat and alternatives, keeping extras (fat and sugars in check).

This program worked for the first two weeks, but in the third week, her weight loss hit a plateau, despite the fact that she had actually only been taking in about 1,250 calories per day. She was not feeling well in our training session and could not concentrate very well.

My questions are: Did this client restrict her calories to a semi-starvation level, causing her body to metabolism muscle? If that is the case, would she not have lost weight anyway? (I highly doubt that she increased muscle mass in one week of weight training to counter the effect of fat loss.)


In regards to the role of fat and carbohydrate metabolism, following are some key concepts:

The human body cannot function without a certain level of carbohydrates present in the body. Most of our main organs including the heart cannot function properly without CHO. In order to compensate for such low levels of CHO, the body will breakdown protein (muscle) in order to produce CHO (glucose). However, this process causes many side effects including Ketogenesis (release of Ketone bodies – they are acidic/ alcohol/acetone based). Excess of ketone bodies in the circulation may cause damage to the heart, liver and kidneys, eventually causing death. That is one reason why someone who is engaged in a very low calorie diet, smells like acetone or alcohol (due to the release of ketone bodies).

Another problem is that the body literally shuts down for its own protection. With such low calorie intake, the body tries to conserve energy by slowing down its metabolism and therefore burning less calories. One often may hear, “I am only eating a 1000 kcal per day and not loosing any weight.” Again, the body literally shuts down as though it is in a starvation mode.

For someone trying to lose weight (or body fat) it would be more realistic to estimate one’s ideal body weight based on the client’s body fat. For a female who is 25 years of age, a body fat of 18 to 20 percent is very good. Weekly weight loss of one to two pounds per week is very realistic. In addition, a calorie restriction of 500 kcals per day would be realistic (250 kcals from food/250 from exercise). 1400 Kcals is too low if the client is exercising as well. More realistic, an intake of 1750 kcal would be more appropriate. Also, do make sure that she has a CHO snack prior to her exercise session.

You can use the Harris-Benedict Equation to estimate her daily caloric expenditure which also takes into account her activity level:

Also, if you know her body fat percentage, you can use the following to estimate her ideal body weight.

Example client: 150 pounds, 30 percent body fat, with a goal to reach 20 percent body fat.

Good luck!