30 pounds in 30 days?

by Mary C. Weaver, CSCS on July 20, 2012

don't fall for the "30 pounds in 30 days" scamWhen I was a middle-schooler, this lame joke was going around: “Want to lose 20 pounds of ugly fat?” [wait for it . . .] “Cut off your head!”

No, the joke isn’t very funny. Its little twist is that it teases you into wanting something that sounds good but turns out to be very bad indeed. You might want to lose 20 pounds, but you sure don’t want to lose your head.

Today I’m righteously ticked about yet another scammy website promising women that they can “lose 30 pounds in 30 days, without exercise.” (What’s worse is that the promoter of this inexecrable crap is actually someone I know.)

Going on a “30 pounds in 30 days” starvation diet is about as sensible as cutting off your head to lose 20 pounds. It might sound good, but it turns out to be a disaster that more or less guarantees a slower metabolism and weight regain.

30 pounds . . . of what?

The point is that when we’re in need of a diet, we don’t need to lose unspecified weight. We need to lose fat. And anyone who could lose 30 pounds in 30 days (especially “without exercise”) would lose a whole lot of water, a whole lot of muscle, and yeah, a modicum of fat as well.

At most (without exercise) you’d probably lose five to 10 pounds of fat. All of those other “pounds” are made up of water and muscle tissue.

The true cost of going on a starvation diet and losing that “weight”—given that much of it is muscle—is astronomical:

  • slowing your metabolism significantly, as a result of both the loss of muscle and the “starvation” effect of cutting calories too dramatically
  • throwing your appetite-regulating hormones out of whack–increasing the ones that turn on hunger and decreasing those that say you’ve had enough to eat
  • the bingeing that typically follows extreme deprivation
  • almost certain weight regain because of the metabolic slowdown and loss of muscle.

Not to mention that when you lose muscle mass through extreme dieting, you end up proportionally fatter, weaker, and less shapely.

Of course, it’s human nature to want a quick fix. I don’t blame consumers who fall for this stuff. I just want to warn them of the dangers of bubonic diets (the kind you should avoid like the plague).

Running the numbers

To see how impossible it would be to lose 30 pounds of fat in 30 days “without exercise,” let’s look briefly at human biology.

A pound of fat represents about 3,500 calories of stored energy. In order to burn that pound, you have to reduce caloric intake and/or increase calorie burn (through activity) by 3,500 calories.

Let’s see how this would work with a hypothetical 195-pound woman. She’s 30 years old, 5’ 6” tall, and sedentary. The Harris-Benedict formula for determining total daily calorie need estimates hers to be about 2,000 calories a day.

She could lose one pound of fat per week by cutting 500 calories a day from her daily intake. And of course, if she exercised regularly, she could burn additional calories and torch more fat. (Becoming “moderately active,” meaning she exercises “moderately” three to five days a week, would bring her daily calorie need to just shy of 2,600!)

But if she purchases the snake-oil solution we discussed above, she expects to lose “weight” without exercising.

As we’ll see in a minute, it’s pretty much impossible for her to lose 30 pounds of fat in 30 days. How can she create a deficit of 3,500 calories a day (one pound of fat) when she only needs 2,000 calories a day to maintain her 195 pounds? Even if she fasted on water alone, she couldn’t cut enough calories to burn a pound of fat a day.

And if she did fast–or even go on a very-low-calorie diet, her metabolic rate would take a rapid nose dive. Either would cause her body to deduce, “Hey, we’re starving. Gotta keep ourselves alive as long as possible, so it’s time to slow the calorie burn way down.”

No, the only way for her to lose a pound per day of fat would be to embark on a Biggest Loser—style training regimen of six+ hours of exercise a day. And even that poses serious metabolic risks.

So please, please, please, don’t give your money to the snake-oil salesmen (and saleswomen). Recognize that they’re selling a lie that can only lead to disappointment.

And that if something sounds too good to be true–like “30 pounds in 30 days without exercise”–it generally is.

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