People often ask questions like:


“How do I lose fat?”

“How much weight can I safely lose per week?”

“How do I know if I am losing fat, water or muscle?”

Luckily a little math can help answer these questions. And you thought it would never be useful after high school!

First, I suggest you Google “basal metabolic rate” and use one of the BMR calculators (or try this one: to see how many calories a day you need just to live, breathe, blink etc. Any activity, such as weightlifting or walking, will add to that number.

Then, all you have to do is make sure you have a slight calorie deficit each day, and you will lose weight. One pound of fat is 3500 calories, so if you have a 400 calorie a day deficit you will lose 7×400=2800 calories per week, or a little less than one pound. If you want to work backwards, then 3500/7=500, so this means you need about a 500 calorie deficit each day to lose one pound of fat (not muscle or water!) per week. This doesn’t sound like much, but if you lose it slowly it’s much less likely to come back.

Why? Well, any more than a 20% calorie deficit and you risk entering metabolic slowdown, or “starvation mode.” If this happens, you will find it more difficult to lose weight, burn fat, and risk gaining back more fat than you lost if and when you abandon or stray from your calorie deficit. In starvation mode, your body would rather burn anything but fat because it thinks food is scarce, so you will start to lose muscle instead, and your slower metabolism and reduced muscle mass makes regaining the fat lost (and then some) more likely.

Do not confuse weight loss with fat loss. Anyone can lose two pounds or more per week if they eat some ridiculously low number of calories like 800 per day, and your bodyweight can fluctuate by 1-2 pounds a day based on factors such as how well/poorly hydrated you are. Muscle weighs more than fat, so if you go on a starvation diet you will lose weight quickly, but it will be muscle that you are saying goodbye to.

It’s also a good idea to check and monitor your body fat percentage. This is the best way to check that you are burning fat rather than water or muscle. Many scales have body fat calculators on them, or you can get some calipers & measure that way. There are also some online estimators based on various body measurements. Some ways are more accurate than others, but the point is to measure and look for nice, consistent drops in your percentage about every week or so. Men are considered “lean” if they are in the 10-15% range, women 16-20%, and “lean” sounds like a nice way to be described!

See for more. I highly recommend Tom Venuto’s ebook “Burn The Fat, Feed The Muscle” if you want to do this right.