It has always seemed to be an automatic assumption that since women do not possess as much muscle mass (or muscle mass potential) as men that somehow resistance training is less important and less well suited for them. As it turns out, proper resistance training is even more important for women because they possess less muscle mass.

There are a couple of new research articles out that I hope will illustrate this point. I will discuss the underlying physiology of my theory on this after we look at these articles. The first article is entitled Effect of Exercise Training Intensity on Abdominal Visceral Fat and Body Composition. The authors are Irving BA, et al. It is published in Med Sci Sports Exerc. 2008 Oct 8.

This article looked at twenty-seven middle-aged (51+/- 9 yrs) obese women with the metabolic syndrome comparing either no intervention, low intensity exercise below the lactate threshold, or high intensity exercise above the lactate threshold. Remember from our discussion in BBS, high intensity exercise is characterized by producing pyruvate from anaerobic metabolism more quickly than the mitochondria can use it. Pyruvate stacks up, and then gets acted on by lactate dehydrogenase producing lactic acid. When this occurs, you are above the lactate threshold.

The really cool thing this article did is that it adjusted the workout times so that the caloric expenditure was identical in both exercise groups. Exercise time was adjusted so that 400kcal was expended per session. This clearly would show that any changes could not be attributed to burning more calories in a particular session. Actually, the calories burned would actually favor the low intensity group since they performed more 400kcal sessions per week.

The subjects’ body composition was evaluated using single slice CT scan at the L4-L5 disc space and mid-thigh to determine abdominal fat and thigh muscle cross-sectional areas. Percent body fat was assessed by air displacement plethysmography (a Bod Pod).

The results were very clear. The high intensity group significantly reduced total abdominal fat, abdominal subcutaneous fat, and abdominal visceral fat. There were no changes observed in the non-exercise group or the low intensity group. The part not mentioned in the study is the most important part. THIS IS VERY IMPORTANT: THE RESULTS ARE CORRELATED WITH INTENSITY NOT CALORIES BURNED. Each exercise session was controlled to expend the same number of calories, AND based on total calories burned, the low intensity group had the advantage since they worked out more days per week. Despite this advantage, the low intensity group did not lose fat. This is a key concept: when it comes to losing body fat you cannot achieve it by “burning calories” in an attempt to influence the calories in/calories out equation. Fat will be mobilized when you use an exercise modality that mobilizes glycogen out of the muscle, creating a need for replenishment via the insulin receptors. As insulin sensitivity improves, serum insulin levels drop and body fat can be mobilized. As this scenario is repeated, triglycerides can be tapped from fat cells to supply energy for high intensity exertion, compounding the fat loss effect.

A similar study was conducted in 2004: The effects of exercise training on abdominal visceral fat, body composition, and indicators of the metabolic syndrome in postmenopausal women with and without estrogen replacement therapy: the HERITAGE family study. Green, JS et. al. Metabolism. 2004 Sep;53(9):1192-6. This study used the same methods for evaluating body composition as the study above. However, the variable studied here is the presence or absence of hormone replacement. There were no significant changes in body composition in either group. The problem with this study is that a low intensity exercise routine was used. Since hormone replacement was the variable studied, it may have been incorrect to conclude it had no value, because it was evaluated in the context of low intensity exercise. If the exercise protocol had been of high enough intensity to actually stimulate results, then perhaps the magnitude of the results would have actually been different with hormone replacement. This illustrates how a study can go awry when it evaluates a given independent variable while using the wrong dependent variables as a backdrop.

Let me take the opportunity to anticipate and address a potential objection to the use of these studies. One objection might be that the high intensity exercise was not done with weights. This is true. But from a metabolic standpoint what is important is that the intensity was high enough to exceed the lactate threshold. Exceeding this threshold is the variable being studied, how that variable is achieved is not important — except that this variable can be achieved much more efficiently and aggressively done the Body By Science way. You must remember that when we use a study to support the premise of BBS, it does not have to be a study that uses exactly the protocol we advocate. We are using studies that look at independent variables that are part of the Body By Science approach. The variable in this case is the concept of high intensity training done above the lactate threshold. Also, Body By Science is not just based on the scientific literature; it is based on an understanding of basic science that has been well ahead of the research curve for over two decades. Stated differently, John and I (and others like us) have relied on an understanding of basic science to construct our exercise philosophy and have shouted our theories from the mountaintops and argued with keepers of the status quo over the decades. Indeed, we have made enough noise throughout the years that our theories are now actually being tested, and there is now data accumulating to support our approach. These are the studies that you will find referenced in Body By Science.

Let me now discuss the basic science that explains why high intensity exercise is even more important for women than for men when it comes to changes in body composition. The metabolic syndrome and the body composition changes that result from it are due to derangements in carbohydrate metabolism. We evolved from an environment of food scarcity where carbohydrate was the least abundant macronutrient, and where high intensity exertion was required to acquire the food we needed. In our modern environment, carbohydrate is very abundant and high intensity exertion is very rare. Most of the carbohydrates consumed are refined and are quickly/easily absorbed. Our evolutionary background has produced a mechanism for signaling energy storage that is predicated on an abundance of what would be the least abundant macronutrient in our ancestral environment. That macronutrient is carbohydrate. What happens in the metabolic syndrome is something that would have been very foreign to our ancestors. We are exposed to very high levels of carbohydrate. This is rapidly absorbed into the bloodstream causing blood sugar to rise, which triggers the pancreas to release insulin so that glucose can be moved into the cells of the body. This normalizes the blood glucose level, and stores the glucose as glycogen for future use. However, your body has limited glycogen storage capabilities. An adult male can store about 70 grams in his liver, and 220 grams in his skeletal muscle. If more glucose than this is present, insulin will then drive synthesis of triacylglycerol, which will, in turn, result in the glycogen being stored as body fat.

The average American consumes way more than 290 grams of carbohydrate in a 24-hour period, even when they are “cutting back” or “watching what they eat.” As this situation compiles on a day-by-day basis, the body adapts by decreasing insulin sensitivity on the muscle cells. This protects the metabolic machinery of the muscle from being jammed with “glycosylation products” by basically binding sugars to proteins within the cell. As a result, insulin sensitivity on the fat cells remains relatively preserved so that excess carbohydrate can be more efficiently shunted towards fat storage. At this point your body has now become a fat-producing factory. You are now in the throws of the Metabolic Syndrome. Now your fat cells are a tissue colony with a competitive advantage. Any nutrition you intake now gets shunted directly to the fat cells. You now suffer from “internal starvation.” You may take in 4,000 Calories per day, but none of it supplies your lean tissue. Your muscle mass, total protein and albumin all drop despite a gluttonous intake of food stimulated by your chronically elevated insulin levels. Why a gluttonous intake? Because LOW insulin levels are needed to tap energy out of fat cells, and with insulin levels being so high, immediate energy needs have to be obtained by the intake of more food (acquired by stimulating hunger)…which then gets shunted to the fat cells. AARRGGHHH!! You are now in the vicious cycle of the metabolic syndrome – but it gets worse: Many of the circulating hormones your body relies now will have glucose attached to them and your body recognizes them as foreign and begins attacking them (this is my theory) and the glands that produce them (thyroid hormone being a prime example).

An article from the Journal of Nutrition and Health A discussion of the relationship between selenium, thyroxine and indigestion. Nutr Health, 1998;12:131-4., suggests that agricultural wheat products have a low selenium content which depresses the activity of the diodinase enzyme crucial to the production of thyroid hormone. Whatever the mechanism, hypothyroidism commonly occurs in tandem with the metabolic syndrome. Now the cycle is truly in lock-down mode. When Oprah asks on the cover of her January 2009 issue of “O” magazine, “How did I let this Happen Again?” I think she might find the answer in the above paragraph.


This situation is more likely to occur in women simply because they DO have less muscle mass than their male counterparts. As a result, their glycogen stores become full more easily and more quickly and the process described above occurs more easily and more aggressively. This is why high intensity exercise is even more important for women. Only high intensity exercise activates the adrenaline-stimulated amplification cascade that mobilizes huge amounts of glycogen out of the muscle. This is a survival mechanism that provides emergency energy for on-site use in our muscles. When you work out HARD (as detailed in Body By Science) you activate this process and empty your muscles of excess glucose. This creates a scenario where glucose needs to be replaced within the muscle. This is done by the action of insulin. Insulin receptors on the muscle surface then become restored, serum glucose can then drop and Insulin levels drop. When insulin levels drop, hormone sensitive lipase can then become active and mobilize fat stores for immediate energy needs. You no longer have to rely on a ravenous appetite to meet immediate energy needs. Before, elevated insulin levels would cause you to misinterpret ANY discomfort as hunger. Now, only energy needs that cannot be met by fat mobilization through hormone sensitive lipase actually stimulate hunger AND it is a subtle signal that it is time to eat (rather than a sense of ravenous panic).

Having detailed the role of high intensity exercise in reversing the metabolic syndrome, I must devote some attention to the dietary aspect of the problem. No exercise program (even high intensity strength training) can compensate for a bad diet that is too high in refined carbohydrate. High intensity exercise certainly gives you more latitude in your diet, but it cannot do it by itself. The diet we advocate is basically a hunter-gatherer diet, which focuses on healthy meats, fats, and carbohydrate derived from fibrous vegetables and low-sugar fruits. What is absent are agricultural-based refined carbohydrates. Anything derived from the seed-head of plants must be ground into flour which is high in rapidly absorbable carbohydrate. Also, seeds of plants contain phytotoxins which help to protect the plant’s reproductive elements from being eaten. These toxins keep animals from reproducing and thriving by disrupting their hormone function. High intake of refined carbohydrate will create the cascade described above. By eating a natural, hunter-gatherer type diet and combining high intensity exercise you can begin reversing the metabolic syndrome.

The important fact to remember is that all of these derangements and their correction occur more quickly in females BECAUSE they have less muscle mass. When eating a modern diet and not exercising, the glycogen stores fill more quickly because less muscle means less storage capacity. When eating properly and performing high intensity exercise, the situation is turned around efficiently because a given amount of glucose mobilization represents a larger percentage of total glycogen stores. Once the situation is reversed, the larger muscle mass represents a larger storage reservoir and more glycogen storage capability. Thus in the future there is more latitude for slip ups before the metabolic syndrome gets a foothold.

When diet and exercise are properly understood, body composition auto-regulates in the ideal range. You are no longer ravenously hungry, to the point that you will often forget to eat. Gone will be the days of weighing food, counting calories, and plodding along on the treadmill for hours. When you eat a proper diet, and partake of high intensity exercise, you set into motion a vicious positive cycle that makes the body you desire easy to achieve.

Compare this to the advice Oprah’s fitness expert gives on page 152 of the magazine shown above when asked to address her relapse:

“Instead of thinking, I’ve failed over and over again, why bother trying again?, take your relapse in stride and stay positive no matter how many attempts it takes you. Each new effort brings you closer to the one that might really work. The key is to stick with it until you achieve your weight and health goals — that’s my definition of a true success story.”

Apparently Mr. Green has not heard the old yarn that the definition of insanity is doing the same thing that has failed you over and over again, and expecting different results this go ‘round.

So to any woman out there who is fed up with trying the same thing over and over, I offer this suggestion, instead of getting back on the treadmill “one more time,” try this: Alter your diet so that you eat no grain-based carbohydrate: no flour, no sugar, no bread, no pasta, and no high fructose corn syrup. Then go to the gym and perform a workout of leg press, pulldown, chest press, row and overhead press. Lift slowly and smoothly but with as much effort as possible. Go to complete fatigue, or as close to it as you can tolerate. Work out once, or at most, twice a week. Make sure your workouts last no longer than 20 minutes. Then sit back and watch what happens.

– Doug McGuff, MD