Calories info... Need some wisdom!

Remember first and foremost, that the purpose of eating calories is nutrition. They say not to go under 1200 because that is how much experts believe you need in order to get your full daily dosage of key vitamins, nutrients, protein, fat, and carbs. Of course you can get your calories from eating a pint of ice-cream, but that's not going to give you nutrition.

When you approach your personal calorie count, it really depends on how much you have to lose. Heavier people are much more able to have larger deficits. Lighter people, much smaller deficits. You just can't pull a number out like 1400 calories and stick to it. Your calorie count needs to come from the facts about your body.

Here is what you can do: First, you need to have a good grasp on how many calories you are expending during the day. I personally use a BodyMedia device to calculate my burn, but you could do this yourself (albeit harder), by figuring out your BMR and adding in your exercise and daily activity calories burned (you will have to recalculate this with every pound lost, since the less weight you carry, the lower your burn). Then you need to find your deficit by subtracting how much you ate from that number.

Now here is the important part: the body is only able to metabolize 31 calories per pound of fat you have per day. That isn't how many pounds you have to lose, or how much you weigh, but actual fat in your body. The doctor can tell you this from several different tests, or you can get this from an average of your evening weigh-ins on a scale that calculates body fat (evening since body fat scales are affected by hydration, and morning weigh ins will over-estimate your body-fat percentage). Your deficit should never go over that number (pounds of body fat * 31), or else you are doing yourself harm by burning your lean mass.

If you are a big person with 100 pounds of fat, your body can metabolize 3100 calories a day from it. So providing you are getting proper nutrition, you can have a large deficit. But if you are a smaller person, you need much smaller deficits. To use myself as an example: I currently have 57 pounds of body fat. 57*31=1767, so my daily deficit cannot exceed 1767 without causing myself harm. I ran yesterday for 2 hours, and BodyMedia calculated my daily burn at 3700 calories. If I only eat 1400 calories, my deficit would be 2300 and my body would take those extra calories by eating my muscle! Therefore, I have to eat back the calories I worked off to make sure I don't exceed my daily deficit. No matter how much you want to, you can't beat body mechanics, and you can't force your body to burn more fat than it is able. Huge deficits, without the fat stores to take them from, are just eating away at the parts of your body you want to keep!

Good luck!

Yes, according to the NIH, your body is indeed capable of metabolizing a full 31 calories per pound of body fat a day. Does this mean that you should eat at such a deficit? Not without doctor supervision. But this explains why - when supervised by doctors - extremely obese people go on huge calorie deficits, consuming as little as 600-800 calories a day. It is how contestants on The Biggest Loser post huge weekly losses at the beginning of the show and a couple pounds by the end. These are supervised to make sure that the foods they are eating are meeting the individual's nutritional needs.

Your personal take away from this is that you can have a higher caloric deficit level (burn minus calories consumed) and eat at a level that meets your nutritional needs and leaves you feeling satiated (protein is your friend), without such concern about really digging into your lean body mass (there is always some inevitable loss, but not like someone eating at a greater deficit than the body can support through fat metabolism). If you want a caloric deficit under 1200 (an arbitrary number which is believed to provide a daily nutritional load), this is something that a doctor should approve to make sure you are getting what the body needs. If you were to fast for a day, for religious or other reasons, your body could metabolize the max amount of calories per pound of fat. There are doctors that recommend fasting, but the majority don't since people tend to binge coming off a fast. So to answer your question, if you indeed had 100 pounds of fat, your body is really able to go at a daily deficit of 3100. Does that mean you should? Ask your doctor. They usually won't recommend it, since they are looking at the long game; they want to see you make long term changes that become habits, and major deficits are for quick weight loss that people usually gain back.

What my post speaks to is more specifically aimed at those on the other end of the spectrum with little weight to lose. Someone who is trying to lose those last stubborn 10 pounds and eats only 1200 calories a day and works out at the gym for a couple hours is hurting themselves. Even if their last stubborn 10 pounds was from 20 pounds of fat, that means the body can only metabolize 620 calories a day - that is all they are able to lose from fat a day. Any other losses are from muscle. If they work out hard, they need to eat back those calories. If they had a daily burn of 3400 calories, they are at nearly double a deficit that their body can support through fat metabolism alone. The body will get the calories from elsewhere, it needs to feed that hungry brain which is a huge consumer, and it will take if from whatever muscle mass it can get it from (including cardiac muscle!)

So for you, be concerned with getting proper nutrition and feeling full (protein at every meal and snack!), and you needn't worry so much about not eating enough calories and loss of lean body mass. When you have lost more weight, you will need to calculate it. I also started with 100 pounds of fat and didn't need to concern myself. But now I'm down to nearly half that, and there are days I need to eat more because my burn is high and my deficit is too great.