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Uncensored Q&A with Lyle McDonald

Lyle McDonald

Lyle McDonald is a physiologist and author who has spent over a decade obsessively finding ways to apply cutting-edge scientific research to sports nutrition, fat loss and muscle growth. In this uncensored Q&A, Lyle answers your most pressing questions about diet and exercise.

Q. I am definitely interested in finding out more about your Rapid Fat Loss Diet but my big concern is will all that weight come back? I have at least 25 pounds to lose. Is it better to lose them slowly? I eat well and count calories, and do cardio at least 5 days a week (and some strength training). Will it backfire on me if I go on the Rapid Fat Loss Diet?

A. My feeling about fat loss is and will always be this: I would prefer, under most conditions, for people to make smaller, less intensive changes to their diets and exercise programs and maintain them. The rapid fat loss program is primarily for extreme conditions, when people MUST lose fat rapidly for some reason.

As far as weight coming back on, it all depends on what you do after the diet is over. If you go back to your old eating habits, you will regain all the fat. If you follow my guidelines (the last four chapters of the book go into great detail on how to best come off the diet), weight regain outside of some water balance issues should be small to non-existent.

However, some research suggests that some initial rapid weight and/or fat loss can be motivating and keep people sticking to their diets in the longer term. One potential use of the rapid fat loss approach is to kick-start a more moderate diet (this is described in the last four chapters of the book).

So, you spend 2-3 weeks on the program to get started, and then move to a more moderate diet (how to set it up is described in those same chapters) to keep the fat loss going.

Q. I am a health and fitness professional and I specialize in weight management. In my experience, it seems that some people are simply weight loss resistant. They are in a negative calorie balance, eat clean foods, consume adequate protein, and exercise, yet the pounds do not seem to budge. Do you have any theories as to why this is?

A. Absolutely and there is some research examining this in humans.

One variable has to do with variation in resting energy expenditure. Even at an identical bodyweight, maintenance calorie intake can vary by 15% in either direction. So, at 70 kilograms (154 pounds) of bodyweight, you might see an energy expenditure that varies from 1700-2200 calories (the average would be about 1950 calories).

If you were to put two people on an identical calorie intake (say 1800 calories per day), the first would actually be gaining weight slowly while the second would be losing nearly one pound per week.

But there is a second factor that is arguably more important: people vary greatly in how quickly and/or how much their metabolic rates drop when you diet them.

In one study, over two weeks of dieting, the drop in metabolic rate ranged from 50-200 calories per day (as I recall, I may have the exact numbers incorrect). So, put two people on an identical diet and one will lose weight much more slowly (if at all).

Other research examined the impact of both fasting and overfeeding in the same individuals. It found that the people whose bodies responded the best to overfeeding (their metabolic rate went up and burned off the excess) responded the least to fasting (their metabolic rates went down the least).

The researchers said these people have a "spendthrift" metabolism: they gain weight with difficulty and lose it easily. The other group had the smallest increase in metabolic rate in response to overfeeding and the biggest drop with fasting, these are the classic "thrifty" metabolisms: they gain weight easily and lose it with great difficulty.

Simply put, some people are truly diet resistant. They lose weight more slowly, and have to diet and/or exercise harder to get the same results. And they gain weight very, very easily.

Unfortunately, the mechanisms behind these processes are poorly studied and understood at this point. I suspect that it has to do with sensitivity to hormones such as leptin, insulin, thyroid and the catecholamines, as well as processes going on in the brain.

For example, people prone to obesity have been found to show low sensitivity to the brain chemical dopamine, which has a number of negative effects in terms of metabolism and appetite regulation.

So, at this point, there are few solutions to the problem other than to diet them harder, exercise them more, or use drugs. My little booklet Bromocriptine talks about the use of the drug bromocriptine (a dopamine agonist) to try to fix some of the problems. Some of the newer weight loss drugs attack other systems in the brain, mainly tryptophan (5-HTP) and noradrenalin to generate similar effects.

Q. We hear a lot about the importance of taking in enough protein to preserve lean body mass as well as to build muscle. Does the protein have to be "complete" for both of these purposes? In other words, if you eat seeds and nuts for some of your meals rather than meat, fish, eggs, dairy or soy, have you got to ensure that you accompany them with grains or legumes?

A. For any readers that are unclear, Geoff is referring to an old idea regarding some proteins being incomplete (in terms of meeting human requirements).

For example, vegetarians were always recommended to combine legumes (beans) with grains (such as red beans and rice) as the amino acid "lacking" in beans is found at high levels in grains and vice versa (the amino acids "lacking" in grains are found in beans). Further, it was thought that incomplete proteins had to be eaten together for the body to utilize them fully.

However, this turns out to be incorrect. With a few odd exceptions (such as gelatin and collagen protein), all dietary proteins contain all of the amino acids. Relative to human needs, it's more accurate to discuss proteins in terms of their limiting amino acid, defined as the amino acid that is lowest relative to what is required for human requirements.

However, even there, given the protein intakes usually seen in athletes and bodybuilders (1 gram per pound of bodyweight per day) and from mixed sources, it's unlikely for there to be any overall limiting amino acid. That is, protein requirement research (in terms of quality and amounts) is usually dealing with folks who are eating
a. low total amounts of protein
b. from a single poor source

Given a high protein intake from mixed sources, common with most athletic diets, I don't consider it worthwhile to worry about complete and incomplete proteins. Worry about total protein intake first. Unless you're getting literally 100% of your protein intake from a single poor source, your body will figure it out.

Books by Lyle McDonald

The Rapid Fat Loss Handbook (e-book)
Maybe you need to drop weight fast for a special event, like a class reunion or a wedding. Perhaps you want to look good in a bathing suit and didn't start your diet and exercise program early enough... or you might just want to get your diet over as quickly as possible. If so, the Rapid Fat Loss Handbook will reveal the fastest, most effective way to shed both weight and fat in the shortest time possible. Now includes FREE home exercise program and easy-to-use online diet calculator.

The Protein Book covers everything you need to know about protein and muscle growth, fat loss and athletic performance. Referencing over 500 scientific studies, the book is the ultimate reference on all aspects of optimal protein nutrition for anyone who's serious about building a better body.

The Ultimate Diet 2.0 (UD2)
The UD2 is possibly the most comprehensive and complete guide to losing stubborn body fat ever written. Inside, you'll discover the secrets of calorie partitioning, how to control where the calories go when you overeat, and where they come from when you diet... the hidden metabolic advantages that elite athletes have, and how to duplicate them to improve your results... why stubborn fat is so stubborn and how to get rid of it... how muscle grows and why so many different training systems can all be right... and much, much more!

A Guide to Flexible Dieting
A Guide to Flexible Dieting reveals how being less strict with your diet can actually make it work better. You'll discover how deliberately breaking your diet (in a controlled fashion) can make it work better in the long run. Free meals, structured re-feeds and even a full diet break are all discussed and explained in detail.

The Ketogenic Diet
The Ketogenic Diet is the first and only book to examine in-depth the scientific evidence regarding low-carbohydrate and ketogenic diets. At 325 pages and containing over 600 scientific references, this will be your complete reference for ketogenic diets. It's unlike any other book on low-carbohydrate diets that you have ever read or seen.

Bromocriptine: An Old Drug with New Uses
The problem of getting very lean or simply losing fat and keeping it off is not a new one. New research is finally explaining the reasons and physiology behind dieting failure and it turns out that many of the problems are in your brain. Bromocriptine: An Old Drug with New Uses explains the physiological reasons behind dieting failures, along with discussing a potential fix: a very old drug called Bromocriptine.