Does fat build muscle?

May 2005


1- Featured Article: Does fat build muscle?

Previously I have been focusing on the true efficacy of several creatine products and formulations currently on the market. This month I would like to change gears a bit and talk about a nutritional issue that could profoundly influence your anabolic hormone levels and ultimately determine the gains you achieve in muscle growth.

Today’s Creatine Newsletter was inspired by a recent slew of questions reaching me from my website. Somewhere, something was said to instigate these inquiries: a press release, a passing comment made by a popular athlete…I suppose l will eventually find the source.

Even so, these questions revealed a great misunderstanding of certain nutritional principals, which is why I chose to address them immediately. These questions have to deal with the effect of fat consumption on anabolic hormone levels. Sadly, in a misguided attempt to accentuate muscle growth many athletes are altering their diets in such a way that they are unwittingly reducing their anabolic hormone levels, instead of bolstering them.

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This Month’s Featured Article:

Does fat build muscle?

by Alfredo Franco, PhD

Types of fat:

Dietary fats, with the notable exception of cholesterol, generally consist of long chains of carbon atoms known as fatty acids. Typically, the carbon atoms within a fatty acid chain concatenate via single bonds, accounting for two bonds per carbon atom. Carbon’s remaining two bonding electrons are dedicated to forming molecular bonds with hydrogen atoms (see figure). In brief, the carbon atoms within a fatty acid chain make four bonds. Typically, two of the bonds are to other carbon atoms within the fatty acid backbone and two bonds are made to hydrogen atoms that emanate from the chain. The word typically is stressed here, because, as should be expected by now, there are exceptions.

A fatty acid is said to be saturated when every carbon atom within the chain is bonding with two hydrogen atoms, or is saturated with hydrogen atoms. Since the number of hydrogen-carbon bonds (red bonds in figure) determines the energy content of a hydrocarbon, saturated fatty acids have the highest energy content (ability to produce the greatest amount of ATP) of any fuel source, particularly when compared to an equivalent amount (in weight) of protein. Furthermore, the oily nature of fats reflects the fact that they exclude water, something that carbohydrates and proteins are unable to do. Consequently, fats are a highly dense source of energy. These physical-chemical properties make fats particularly well suited to being nature’s long-term energy storage molecule? In fact, 98% of our entire energy reserves lie within fat deposits. Unfortunately, energy density is not everything. The hydrogen-carbon bonds held within fats are somewhat difficult for the cell to access, which is why carbohydrates (sugars and starches) are still quicker sources of energy.

Long-chain saturated fatty acids tend to pack tightly together and, hence, have restricted mobility. This, in turn, means that saturated fatty acids of more than 16 carbons in length are solid at room temperature. Natural sources of saturated fats are in fact mixtures of several different fatty acid species and commonly arise from animal sources. Examples include cheese and butter. Nevertheless, some plant oils also possess significant levels of saturated fatty acids, including coconut and palm oils.

Unsaturated fatty acids contain carbon atoms connected by double bonds within the chain. Obviously, a carbon that bonds twice with a neighbor has fewer bonds available to make with hydrogen. That is, a double bond unsaturates a fatty acid chain. More importantly, a double bond creates a kink in the fatty acid chain. The downstream effect of this is that unsaturated fatty acids cannot pack as closely together as saturated fatty acids. They are therefore liquid at room temperature. Most vegetable oils are sources of unsaturated fatty acids. The figure shows an example of an unsaturated fatty acid possessing a single double bond – a monounsaturated fatty acid. Olive and canola (rapeseed) oils are good examples of monounsaturated fats.

Polyunsaturated fatty acids contain multiple double bonds within the fatty acid chain making them contort into rather complicated shapes. The omega-3 fatty acids are examples of polyunsaturated fatty acids that are very important to overall health. However, despite their extreme importance, polyunsaturated fats will not be dealt with today, but will be the topic of a subsequent issue of the Creatine Newsletter.

The fat-muscle connection:

Testosterone is one of our principal tissue-building hormones. Testosterone is also responsible for the expression of secondary sexual characteristics in males. Testosterone is thus anabolic and androgenic, respectively, which is why females typically cultivate less muscle mass than males.

Expectedly, diet influences the production of our anabolic hormones. The specifics, however, certainly remain sketchy to most. Early studies have hinted at an interaction between dietary fat intake and serum testosterone levels. In particular, it has been shown that athletes consuming diets containing 40% fat expressed greater serum testosterone levels than athletes consuming a diet consisting of only 20% fat. Nevertheless, the exact type of fat responsible for this effect remained unknown for some time.

One of the most potent stimulators of testosterone release is exercise, which is the reason why that exercise typically stimulates muscle growth. Unfortunately, exercise also liberates cortisol, our principal catabolic, or tissue consuming, hormone. An overproduction of cortisol will completely undo the anabolic effects of testosterone. Therefore, the trick for someone trying to build muscle mass is to provide an exercise stimulus that releases sufficient amounts of testosterone to build muscle, while keeping cortisol release to a minimum.

Study Title:Testosterone and cortisol in relationship to dietary nutrients and resistance exercise.

The study examined the hormonal responses of twelve fit males to approximately 20 minutes of resistance exercise. Five minutes after performing 10 sets of bench press and 10 sets of jump squats serum levels of testosterone and cortisol were measured and correlated with dietary patterns. The subjects were asked to report all they had eaten for 17 days prior to performing the exercise session. The strongest positive correlation found was between dietary fat intake and resting testosterone levels. Diets containing greater amounts of fat were associated with higher levels of free testosterone at rest. Interestingly, a strong negative correlation was found between protein intake and pre-exercise testosterone levels. This finding is very important in light of the fact that many athletes limit their intake of fats, while increasing protein intake in an attempt to gain muscle mass. Obviously, this would have the exact opposite effect on testosterone release as desired and will consequently interfere with muscle growth.

The results from this study are summarized below.

Approximately 20 minutes of resistance exercise was sufficient to raise serum testosterone levels significantly.

  • The exercise consisted of 5 sets of bench press (10 repetitions to failure) and 5 sets of jump squats (10 repetitions at 30% of each persons maximum squat) with 2 minute rest intervals in between sets.
  • Jump squats released larger amounts of testosterone, due to the greater amounts of muscle mass recruited in performing the tasks. In other words, large multi-joint movements release more testosterone.

However, this exercise regimen was not enough to raise serum cortisol levels.

  • Reducing the rest intervals by half (one minute) may have been enough to induce the release of cortisol.
  • Therefore, 20 minutes of resistance exercise is sufficient stimulus to release testosterone, while avoiding the release of cortisol!!

Diets containing greater amounts of fats were correlated with higher resting testosterone levels.

  • Specifically, the consumption of saturated fats was strongly correlated with higher resting levels of testosterone.
  • Monounsaturated fats were the next highest predictor of resting serum testosterone levels.
  • The absolute levels of polyunsaturated fats had no effect on serum testosterone levels.
  • The increments in serum testosterone observed after exercise were not influenced by diet.
  • -Measuring serum testosterone levels at 5 minutes post-exercise may have been to soon to reveal an effect of diet on post-exercise testosterone levels. Later time points may be necessary to unveil a possible effect.

Surprisingly, higher protein diets were negatively correlated with plasma testosterone levels.

  • The type of protein appears to matter. Previous studies have shown that animal protein is more effective at raising stabilizing serum testosterone levels than vegetable or egg proteins.

There was no apparent effect of nutrition of resting cortisol levels.


We live in a fat-phobic society. It now seems, however, that a little bit of dietary fat is a good thing as far as testosterone is concerned. Given the results of this study, I recommend that daily fat comprise 15-20% of your diets, especially while undergoing heavy training. Protein should comprise 25-30% of your diet as to supply an adequate amount of substrates for the production of new muscle tissue. Finally, carbohydrates should make up about 60% of your diet to maximally stock your energy reserves. It is also important to keep you training sessions intense, but brief, as to avoid the release of cortisol, but to stimulate the release of testosterone.

I will discuss in subsequent issues of the Creatine Newsletter exactly why fats have this effect on serum testosterone levels, as well as how to specifically combine carbohydrate and protein intake for an optimal anabolic status.


Despite the findings of this study, DO NOT adopt a more is better mentality concerning the intake of saturated fats. It is important to keep in mind that diets high in saturated fats also greatly increase your chances of developing Coronary Heart Disease (CHD) in later life. On the other hand, monounsaturated fats have been shown to have a positive influence on serum cholesterol levels and, consequently, help protect against CHD. Therefore, canola oil (a monounsaturated fat also known as rapeseed oil) may be a worthwhile addition to your diet since it has a positive effect over free testosterone levels as well as contains valuable polyunsaturated fats. Elevated testosterone levels may also predispose one to certain types of cancers.

Scientific References

Jeff S. Volek, William J. Kraemer, Jill A. Bush, Thomas Incledon and Mark Boetes (1997) Testosterone and cortisol in relationship to dietary nutrients and resistance exercise. Journal of Applied Physiology Volume 82 (1), pages 49-54.

Read a newsletter issue discussing the benefits of combining creatine and conjugated linoleic acid supplementation over the typical loss of muscle mass and increase in body fat observed in the elderly.

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