No problem - this is a good thread for it.
how many pounds of fat can one lose in a month? Is it based on percentage of what you already weigh?
Yeah, it's going to be based on a percentage of your weight. Someone who has more excess fat is going to be able to shed more of it than someone who has less. IN general, the figure to shoot for is around 1% of your total bodyweight per month. That's losing both fat and muscle because you're going to lose some of each. The way to skew towards more fat and less muscle is to do some kind of strength training and make sure you're consuming enough protein. I remember reading an article that most people lose around 50/50 fat and lean mass, but people who are lifting weights and consuming sufficient protein can skew that to be closer to 75/25 (more fat than muscle). I really hate people who post "I read somewhere" so I promise I'll go find the resource for that figure ... or find the correct ones.
But in the back of my mind I know that's close to what I read.
And how do you figure the calories per day to make sure you don't go below and put your body into starvation mode? I've heard some people say multiply your weight by a certain number, some say 12 or 13, which sounds really high for someone like me, but don't go below 1200.
The technical numbers use the Harris Benedict equation, which takes into account your age, height, and weight to find your BMR (basal metabolic rate - or in other words the number of calories you need to survive if you did nothing but lie in bed all day and breathe.
). The actual calculations for BMR are:
Men: 66 + (13.7 x weight in kilos) + (5 x height in centimetres) - (6.8 x age in years)
Women: 655 + (9.6 X weight in kilos) + (1.8 X height in cm) - (4.7 X age in years)
Then you multiply that by an activity level multiplier based on how active you are (desk job, work out 2-3 times a week, on your feet all day, etc.).
You can get awfully close to that for 90% of everyone (except the extremely obese and the extremely underweight) by estimating 14-16 calories per pound of bodyweight to MAINTAIN current weight for someone who is moderately active (i.e. exercises 3x a week or has a reasonably active job). I've put the calculation into a spreadsheet and run upwards of 100 variations, and the 14-16 calories times bodyweight always comes out to within 5% variance of going through the HB equation. So I am very confident using those figures for most people (barring medical issues, drug use, etc.).
So if you use those numbers for maintenance, you can figure a reasonable and healthy drop in calories (one that will still cause weight loss w/out causing too much of a metabolic slow down) is about 20% to 30%.
So putting those figures into real world numbers, let's use me. I weigh 170 today.
170 * 14 = 2380 calories to maintain
2380 * 70% = 1666 calories to lose.
So if I am at a 30% deficit of calories, I should be able to lose weight at 1600-1700 calories.
Just to verify that, I can put my age, height, and weight into the HB equation (41, 5'4", 170) and come up with 2422 maintenance and 1696 at a 30% deficit.
If you want to simplify that even more, you just take the maintenance calorie figure (14) and drop 30% from that. So 70% of 14 = 10 (rounded up). So if I multiply my weight by 10, that's the number of calories I should eat to lose weight.
It's actually pretty darned easy - people want to make it harder than it is.
Now, as far as the starvation response ... well that's a whole 'nother issue.
The truth is that any time you drop your calories, you're triggering a metabolic slow down. But you're never going to drop your metabolism so low that you stop losing weight. If you're eating fewer calories than you're burning, you will lose weight. But you can drop your metabolism to the point that your body stalls for a period of time as it tries to adjust, whic his where weight loss stalls come from and the whole "starvation mode" semi-myth has been blown out of proportion.
The bigger problem when you drop low enough in calories is not so much about metabolism any more - it's about your body beginning to cannibalize itself. Your body will turn towards burning your own muscle before it allows you to starve. And your heart is a muscle. Most people who die of starvation? Anorexics? Most of them die of heart failure because their body has begun to eat it's own muscle tissue for nutrition and their hearts are so damaged they can't continue to live.
I think there was a thread here recently with a news article about a bride who died because she was on a 500 calorie a day diet to try to fit into a wedding dress. That's what happened to her - she dieted herself into heart failure from electrolyte imbalances and damaged heart muscles.
