The Zone Diet
"Enter the Zone" by Dr. Barry Sears is the book that has sparked so much interest lately among dieters, athletes, and health professionals. On the cover Sears claims that you can "lose weight permanently, reset your genetic code, prevent disease, achieve maximal physical performance, and enhance mental productivity". These lofty claims are only the first in a series of red flags that has most every health professional steering clients away from the Zone. Other names for this diet are the 40-30-30 plan, PR Diet or PR Bar, or simply the generic low carbohydrate high protein diet.
In the first pages of the book, Sears describes what life is like in The Zone: "solutions to problems become more obvious ... fatigue is replaced by high competence ... weight loss is painless and automatic ..." Apparently the Zone is supposed to be this euphoric state in which you float through life and nothing ever gets to you.
So, what exactly is "The Zone"? One of the many problems with this book is that The Zone is really never clearly defined. Sears suggests it is "a real metabolic state in which the body works at peak efficiency". A real metabolic state vs. a fake one? I thought all metabolic states were real! And what is peak efficiency? It could mean a hundred different things to a hundred different people. Another stab at a definition: " where the body makes more good than bad ecosanoids". Ecosanoids are hormones in our bodies which control things like the inflammatory response and blood clotting. The problem is, and Sears is the first to admit this, these hormones are almost impossible to measure accurately. They're not in the blood stream for very long and they're very fast acting.
How does one enter this ill-defined and immeasurable state? Another quote: "to get your passport to The Zone, you must treat food as if it were a drug. You must eat food in a controlled fashion and in the proper proportions, as if it were an intravenous drip." That doesn't sound like very much fun! If there is one thing I've learned as a nutrition professional, it is that nourishing our bodies is only one of the many reasons we eat. Food is also meant to be pleasurable, comforting at times, and in our society countless social events and even some cultures are centered around food. But Sears wants us to follow a set of rigid dietary rules and he wants us to eat the correct proportion of carbohydrates (CHO), protein, and fat at all times.
As I'll explain later, most people who say they are following the Zone really aren't. However, they still tend to buy into the major claims made by Sears in the book. Let's go over the major claims and discuss why they are wrong or unfounded.
CLAIM # 1: Carbohydrates are the reason you are fat.
According to Sears, a high CHO diet causes increased insulin levels, which in turn increases the storage of fat. He's right about the first part ... CHO does indeed increase insulin levels , but this does not necessarily mean that you will store fat. The primary fate of ingested CHO is in maintaining (1) blood glucose levels, (2) muscle glycogen stores, and (3) liver glycogen stores. The average person can store roughly 500 - 600 grams of CHO (athletes can store more due to more muscle) in these "tanks". Since these tanks are easily depleted on a daily basis, especially in an active person, we need constant replenishment of CHO. On the other hand, we would probably do OK for a couple days without protein or fat. This is because we have sufficient storage capacity for them. Protein is stored in the muscle and in other amino acid pools. And fat ... well most of us would be able to tell you exactly where that is stored. Yes. CHO can be stored as fat - BUT ONLY IF WE CONSUME MORE THAN WHAT WE NEED. It is extra calories (from CHO, protein or fat), not extra CHO that is the culprit in fat storage.
CLAIM # 2: Americans are fatter because we are eating less fat.
Sears blames our epidemic of obesity on the advice from health professionals to eat less fat and more CHO. He says most health professionals recommend 70% CHO, and 15% protein and fat. Actually, most nutrition experts / dietitians, including myself, recommend more like 50-60% CHO with 10-15% protein and 20-30% fat - depending on the individual. I don't think I've ever recommended anyone go below 20% of their calories from fat, even elite athletes. Again, extra calories seems to be why people have gained weight. Data from the National Center for Health Statistics reveals Americans are, on average, eating about the same amount of fat on a daily basis (about 80 grams) but about 200-300 extra calories per day. I do think that some very well meaning people have taken the advice of nutritionists and thought "well if low fat is good, then no fat must be even better." I've seen diets that were 90% CHO, with maybe 5-10 grams of fat per day. This low fat intake can often cause someone to overeat CHO, making them gain weight. And what about exercise? - Sears never once mentions exercise. Couldn't lack of exercise be the reason we are fatter in our society of convenience? In my opinion, you simply can't talk about weight loss without talking about exercise.
CLAIM # 3: Dietary fat doesn't make you fat.
This is true if you don't eat fat in excess of what you need (sound familiar?) However, the thermic effect of protein is greater than that of CHO, which is greater than that of fat. What this means is that CHO and protein are not stored AS EASILY as fat on the body as fat is. And it makes sense ... the body has to work a little harder to change a protein or CHO molecule into a fat molecule, but fat is already in the right form, the body just has to store it! In addition it is easier to overeat fatty foods, as they take up less space and have more calories per gram than either protein or CHO. CHO foods like beans, legumes, and whole grains are bulkier and it is harder ( but not impossible) to overeat these foods.
CLAIM # 4: Increased CHO diets impair athletic performance.
An amazing statement given the virtual avalanche of evidence to the contrary. A number of "classic" studies (Costill and Miller, 1980, Wilmore and Costill, 1988) have proven time and again that CHO is essential to the performance of athletes, especially endurance athletes. In one study, subjects performed 2 hours of cycling each day for three days. One group (interestingly) was put on a 40% CHO diet and the other was put on a 70% CHO diet. The researchers measured muscle glycogen levels, and those on the 40 % CHO diet had depleted levels by the end of the three days, while the 70% groups glycogen stores remained close to initial levels throughout the study.
CLAIM # 5: The correct balance of insulin to glucagon controls the production of ecosanoids.
Researchers believe ecosaniod production is more dependant on our consumption of omega-3 fatty acids than anything else. I said before that most people who say they are following the Zone really aren't ... this case study will help to demonstrate why.
CASE STUDY: 24 year old female, 25% body fat, 135#, moderately active
The first thing Dr.Sears has you do is determine your body fat percentage. He uses a method known as the circumference method. You basically take a tape measure and measure the width of your thigh, waist, torso, etc. This is probably the least accurate way known to man to determine body fat. Why? Because if I'm a bodybuilder my thigh is going to be huge, but that hardly means I have a lot of body fat.
Next you determine how much lean mass you have. Then, with that number you multiply by a protein activity factor (.5 - sedentary up to .9 for an athlete) to come up with your protein allowance for the day.
For our 24 YO female: 135# x .25 = 34# fat and 101# lean 101# x .7 (moderately active protein activity factor) = 71 gms protein
Sears has you break up your protein allowance into "blocks". There are 7 grams of protein per block so our female would get 10 blocks of protein. For every block of protein, you get one block (9 gms) of CHO and one block (1.5 gms) of fat.
This gives our female a grand total of 775 calories!! And here's something interesting - the distribution of these calories is 36% protein, 46% CHO, and 17% fat. What happened to 40-30-30?
Well, I went through all of that to show you that the Zone is nothing other than another hypocaloric diet in disguise. This female would require more like 2100 calories to maintain her weight and a couple hundred less if she wanted to lose. This is one reason I believe that most people are not really following the Zone to the letter. If they are, it usually only lasts for a short time because hunger and fatigue eventually take their toll. Usually when someone tells me they're on the Zone I try to probe them a little further by asking how many calories they are consuming or how many blocks of protein they're eating. The answers to these questions usually reveal something other than the Zone. The other reason people can't usually follow the Zone can best be summed up in the snacks Sears recommends on page 261:
Boston Cream pie with .... well you get the idea
Amazing ... snickers, ice cream, and beer are OK, yet bagels, bananas, cranberries, carrots, and pasta are out of the question.
What about consuming adequate calories while maintaining the 40-30-30 distribution? Well, technically, you wouldn't be in the Zone. I don't think this distribution of calories is particularly dangerous unless you are an athlete or a person with kidney disease, diabetes, heart disease, osteoporosis, or if you have any of the risk factors for those diseases. Thirty percent protein puts a lot of strain on your liver and kidneys to get rid of the urea, 30% fat is a little much for those with heart disease or diabetes, and high levels of protein in the diet cause you to spill calcium in the urine - not good for someone with osteoporosis. Even if you are totally healthy, I would not recommend being on a high protein diet for any length of time.
When you come across a diet that you're not sure about, use the following characteristics to evaluate whether or not it's just a fad.
CHARACTERISTICS OF A FAD DIET
The best diet is still one that is moderate in protein and fat, and contains plenty of fruits, vegetables, and whole vs. processed foods. And of course, exercise is the best way, along with a healthy diet, to maintain a healthy weight throughout life.
For more information, please contact the Nutrition Office at 621-4550.
Written by: Paige Holm, R.D.