Rapid Fat Loss Handbook

Lyle McDonald's 93-page diet guide

A Scientific Approach to Crash Dieting

Excerpt

Chapter 1: Just how quickly

I've started my last two books with a chapter (or 5) addressing a specific problem, then working to what I consider the solution. I'm going to spare you that endless verbiage this time and jump right into the main topic. Since this is a book about rapid weight/fat loss and crash dieting, I imagine all of my readers want to know just how quickly fat and/or weight can be lost. Before I can answer that question (and even to clear up what I suspect may be some confusion by my readers on the previous sentence), I have to cover a bit of physiology first.

I always figured that somehow the body could 'tell' how much you were eating by some signal from your stomach in relation to the amount of food you ate, and that it used that to judge how much you were (or weren't) eating. While there is a hormone, ghrelin, that is released from the gut in response to food intake, it doesn't turn out to be the signal that is really important. Two years ago, I found the part of the puzzle I was lacking which at least defined and explained the problem. Fixing the problem has been more difficult.

Weight versus fat: they are not the same thing

Every tissue in your body (including muscle, bodyfat, your heart, liver, spleen, kidneys, bones, etc.) weighs a given amount. We could (conceivably anyhow) take them out of your body, plop them on a scale and find out how much they weigh. Your total bodyweight is comprised of the weight of every one of those tissues. But only some percentage of your total bodyweight is bodyfat.

Researchers and techie types frequently divide the body into two (or more) components including fat mass (the sum total of the bodyfat you have on your body) and lean body mass (everything else). Without getting into unnecessarily technical details about different kinds of bodyfat, let's just go from there.

Let's say that we could magically determine the weight of only your fat cells. Of course, we know your total weight by throwing you on a scale. By dividing the total amount of fat into the total bodyweight, you can determine a bodyfat percentage which represents the percentage of your total weight is fat.

Lean athletes might only have 5-10% bodyfat, meaning that only 5-10% of their total weight is fat. So a 200 pound athlete with 10% bodyfat is carrying 20 lbs (200 * 0.10 = 20) of bodyfat. The remaining 180 pounds (200 total pounds - 20 pounds of fat = 180 pounds) of weight is muscle, organs, bones, water, etc. Researchers call the remaining 180 pounds lean body mass or LBM. I'll be using LBM a lot so make sure and remember what it means: LBM is lean body mass, the amount of your body that is not fat.

In cases of extreme obesity, a bodyfat percentage of 40-50% or higher is not unheard of. Meaning that nearly 1/2 of that person's total weight is fat. A 400 pound person with 50% bodyfat is carrying 200 lbs of bodyfat. The other 200 pounds is muscle, organs, bones, etc. Again, 200 pounds of LBM.

Most people fall somewhere between these two extremes. An average male may carry from 18-23% bodyfat and an average female somewhere between 25-30% bodyfat. So a male at 180 lbs and 20% bodyfat is carrying 36 pounds of fat and the rest of his weight (144 lbs) is LBM. A 150 pound female at 30% bodyfat has 50 pounds of bodyfat and 100 pounds of LBM.

I bring this up as many (if not most) diet books focus only on weight loss, without making the above distinction. I should note that more current books have finally started to distinguish between fat loss and weight loss.

Why is this important?

So let's say you start a diet, reducing some part of your daily food intake. Maybe you start exercising too. After some time period, you get on the scale and it says you've lost 10 lbs. That's 10 lbs of weight. But how much of it is fat? Frankly, you have no way of knowing with just the scale (unless it's one of those Tanita bodyfat scales, which attempt to estimate bodyfat percentage but more or less suck, by the way). You could have lost fat or muscle or just dropped a lot of water. Even a big bowel movement can cause a weight loss of a pound or two (or more, depending). A colonic that clears out your entire lower intestinal tract may cause a significant weight loss. The scale can't tell you what you've lost, it can only tell you how much you have lost.

When you're worrying about long-term changes, the real goal is fat loss (some LBM loss is occasionally acceptable but that's more detail than I want to get into here). That is, cycling water weight on and off of your body (as frequently happens with certain dieting approaches) isn't really moving you towards any real goal even if makes you think you are. Don't get me wrong, it may be beneficial in the short-term (again, I'll talk about reasons to crash diet shortly) but it doesn't represent true fat loss.

My point in bringing up this distinction is that it's easy to hide the true results of a diet by not making the distinction between weight loss and fat loss. In many diets, and in the case of the crash diet I'm going to describe, total weight loss will drastically outstrip true fat loss. As above, this may have benefits or not but I wanted to make sure everyone was clear coming out of the gate. I also don't want to get accused of misleading my readers by making them think that the total weight loss is all fat loss; it's not.

Just how quickly

So just how quickly can you lose fat (or weight for that matter)? Most mainstream diet books and authorities echo the idea that 2 lbs per week (a little less than 1 kilogram per week for the metrically inclined) is the maximum. Where did this value come from? Frankly, I have no idea.

To at least some degree, it probably represents about the maximum weight/fat loss that most feel should be attempted. To understand this, I have to do a little bit of math for you. One pound of fat contains roughly 3,500 calories of energy. Therefore to lose two pounds of fat per week (this assumes that you are losing 100% fat which turns out to be a bad assumption) requires that you create a weekly deficit of 7,000 calories.

Meaning you either have to restrict your food intake or increase your energy expenditure (with exercise or drugs) by that much. Obviously, that averages out to 1,000 calories/day. You either end up having to restrict food pretty severely or have to engage in hours of exercise each day. From that perspective alone, losing faster than 2 pounds per week is considered unrealistic or unwise.

At the same time, it's not uncommon to see claims of weight losses of one pound per day or 3-5 lbs per week on some diets. In the initial stages of some diets, weight losses of 15-20 pounds are not unheard of. Are these all lies? Not exactly. Part of it has to do with the issue of weight loss and fat loss discussed above. An extremely large individual, put on a restrictive diet can probably lose significantly more than two pounds of weight per week. But it's not all fat.

This is especially true for the myriad low-carbohydrate dieting approaches out there. Studies demonstrate a rapid weight loss of anywhere from 1-15 lbs in the first week or two of a low-carbohydrate diet and average weight losses of 7-10 lbs in the first week are fairly standard. Most of it is simply water loss although some of it will be true tissue loss, meaning fat and muscle. After that initial rapid weight loss, true weight/fat loss slows down to more 'normal' levels.

The same goes in reverse, by the way, when you take someone on a low-carbohydrate diet and feed them carbs again, it's not uncommon to see weight spike by many pounds very quickly. A high salt intake can cause a rather large retention of water (especially if you've been on a low-salt diet) and most women will readily tell you about the rapid weight gain (from water retention) that occurs during their menstrual cycle.

Why does it matter?

I bring this up for the simple reason that the diet I'm going to describe is going to cause both rapid weight and fat losses. Just realize that the total weight loss (which may range from 10-20 lbs over 2 weeks) isn't all comprised of bodyfat and I don't want to play the rather intellectually dishonest game of making you think it does. A majority of it is going to be water loss. As discussed next chapter, this isn't necessarily a bad thing.

Diet overview

Tho I'll give you many more details in an upcoming chapter, the diet described in this book is simply a slightly modified protein sparing modified fast (PSMF), a very low calorie diet consisting of lean proteins (amounts varying depending on specific circumstances), a small amount of fat and carbohydrate, a more or less unlimited amount of no calorie vegetables (and other zero-calorie foods), some basic supplements, and nothing else. On average, caloric intakes will come out to be about 600-800 calories/day coming almost exclusively from protein. For those of you familiar with such diets, a PSMF is essentially a ketogenic diet without the dietary fat. Obviously, this will represent a fairly large caloric deficit; how large depending on your starting bodyweight and activity levels.

Quick tangent: didn't some people die?

Older dieters or just historians of the field may remember that there were some deaths in the late 70's and early 80's in individuals following something called The Last Chance Diet. This particular diet was a protein sparing modified fast centered around supplemental liquid nutrition but the folks who developed the product couldn't have done a worse job in designing it. First they picked the cheapest protein source available, collagen; a protein that provides essentially zero nutrition to the body. Second, they provided zero supplemental vitamins and minerals (some of which would have been obtained if the dieters had been eating whole foods in the first place). This caused a couple of problems including cardiac heart loss (from the total lack of protein) and arrythmias from the lack of minerals. Basically, the problem wasn't with the approach so much as with the food choices. PSMF's based around whole foods (which provide high quality proteins as well as vitamins and minerals) and with adequate mineral supplementation have shown no such problems.

What can you expect?

So with all of that in mind, you may still be wondering what you can expect in terms of true fat loss per week. A lot of it, actually, will depend on where you're starting out bodyweight wise (activity also factors in), as that determines your maintenance caloric level.

A 165 pound male with normal activity patterns may have a maintenance requirement of about 2700 calories/day. At 800 calories/day on this diet, that's a 2000 calorie/day deficit, 14000 calories over a week, 28000 calories over 2 weeks (note: there is a slowing of metabolic rat that reduces these values somewhat). Assuming all of the true (non-water) weight lost was fat (it won't be), that should be an 8 pound fat loss in 2 weeks (28,000 / 3,500 = 8) or approximately 2/3rd of a pound of fat lost per day. The true fat loss will be lower because of various inefficiencies and the slowdown of metabolic rate (which can start after only 3-4 days of severe caloric restriction).

A larger individual, say 250 pounds, may have a maintenance caloric requirement near 3,750 calories per day. At 800 cal/day on this diet, that's a 3,000 calorie/day deficit. Over 2 weeks, that's a 42,000 calorie deficit, divided by 3,500 calories/pound of fat equals 12 pounds of fat. That's on top of the 10 or more pounds of water that may be lost.

Females or lighter individuals with their generally lower maintenance caloric requirements will lose less. True fat losses of 1/2 pound per day or slightly less may be all that they get: that still amounts to a considerable fat loss (7 pounds over 2 weeks) along with the extra water weight loss.

The bottom line being that an approach such as the crash diet can take off both fat and weight far more rapidly than less extreme diets. And while I still think it's generally better for dieters to take the long-approach and use less extreme diets for longer periods of time, as I'll discuss in the next chapter, under some circumstances, crash dieting can be beneficial.

Click here to read an excerpt from Lyle's book, A Guide to Flexible Dieting

Click here to read about Lyle's book, The Ketogenic Diet

Click here to read about Lyle's book, The Ultimate Diet