Sunday, July 17, 2011

Can You Live on 700 Calories a Day?

Hi, I was just wondering how viable it would be to live on 500-700 calories a day?
Chrys T.

Hi Chrys,
There are many variables in determining a person's calorie needs: Among them are gender, height, weight, age, and activity level. The range is broad and typically goes from about 1700 to over 3000 calories for weight maintenance.

Basically, any person would need at least 1200 calories to meet their nutritional needs. If you went on a very low calorie diet (like 700 calories) you would lose weight fairly quickly, and that might be alright for a few weeks if that was your goal. But after a while you would begin to suffer deficiencies: First, the water soluble vitamins like riboflavin and vitamin C, and much later other vitamins like A and D.

You might ask, "Why couldn't I just take a vitamin pill?". Well, you could, but you would also have to make sure it was full of minerals, and electrolytes (like iron, calcium and sodium) to meet your needs. Then you would still be missing a source of essential fatty acids, protein, and fiber. You could take these all in a pill or powder, too, but we still don't know what other elements are in our food, yet to be discovered, that would be missed.

In the long term, your body would try to compensate for you 'starving' it, and slow down your usual metabolism. Your weight loss would eventually slow down, and when you tried eating a normal amount again you would quickly gain weight. This is what happens to "yo-yo" dieters who go on a low calorie diet, lose weight successfully, go back to eating normally and gain the weight, finally disturbing their normal metabolism and staying overweight their entire life.

If you were referring to the study that had people with diabetes go on a 600 calorie diet to reverse their diabetic condition, they only stayed on this for a few weeks (Diabetologia. published online June 24, 2011). The key to reversing diabetes (type 2) is usually weight loss, and that could be accomplished over time on a much more reasonable caloric intake.