Our physical and mental health as well as various aspects of the aging process depend directly on our body's hormones. Some hormones play a bigger role than others, and we can definitely manipulate them to some degree through diet and environmental factors. Many dietary recommendations we get through the media are wrong for optimizing these hormones and are leading to the obesity epidemic we are experiencing today.
Three of the most important hormones for changing your body composition and enabling peak performance are human growth hormone (GH), testosterone and insulin. All three of these are anabolic which means that they have a direct effect on increasing muscular size and strength. Testosterone and GH also are lipolytic, which means they help the body burn fat as energy and will reduce your body fat. Insulin is lipogenic if too much is released, which means it will actually tell the body to store body fat. These are the three hormones that will have the greatest effect on your body composition and mood and are the easiest to manipulate through your diet.
The glycemic index is a chart which ranks foods based on how much a particular food will spike your blood sugar. Sample charts of the glycemic index can easily be found online. When your blood sugar is high, your pancreas releases insulin to bring down blood sugar levels. When insulin levels rise, growth hormone secretion is significantly decreased. Conversely, GH levels increase just as significantly when insulin levels are low. Which foods will cause the greatest rise in blood sugar and the consequent insulin release? Primarily carbohydrates, and some cause a greater increase than others. High glycemic foods will spike blood sugar more than low glycemic foods and will completely suppress GH release. Eating some fat with carbohydrates can blunt this rise in blood sugar. This is why a low fat, high carbohydrate diet is devastating to trying to optimize your growth hormone levels and could be leading to your inability to lose body fat.
Our body releases the most growth hormone at two different periods throughout the day. The first period is while you are asleep. This is why eating carbohydrates right before bed, such as a bowl of cereal, is a bad idea as it will blunt this crucial release of GH. Going to sleep with a high blood sugar will completely nullify your night time growth hormone release. High quality protein on the other hand can increase GH levels, so the best approach if you are going to eat before bed is to have protein, or limit carbohydrates for at least two hours before bedtime.
The second spike of growth hormone secretion can occur in response to exercise. The more intense the exercise, the greater the release you will get. This is why if you are going to do cardio, high intensity interval training (HIIT) will be more beneficial then steady state cardio for fat loss. HIIT is a type of training where you get as close to an all out sprint as possible for a short period of time, followed by a much slower pace for an equal or greater length of time to recover. Doing HIIT for even half the duration of steady state cardio will release more GH because of the short bursts of all out exertion and therefore give a far greater fat loss benefit.
Weight training will provide an ever greater GH release, especially compound movements which require maximum effort such as deadlifts, squats and presses. High intensity weight training will cause a 400% increase in GH as opposed to 166% from riding the bike at a high intensity. This is why you will actually cause a greater change in your body composition and reduction in body fat from weight training than you will from cardio.
So what is the best way to eat before and after a workout to make sure we are maximizing our hormone response to give us the best possible results? A common assumption is that we need a high carbohydrate meal before we workout to give us energy, and then more carbohydrates after to replenish glycogen stores. I have made these same mistakes and recommendations myself. Eating carbohydrates right before you workout puts a halt to exercise-induced growth hormone secretion. A high carbohydrate meal can also make you feel sluggish and adversely affect motivation and energy levels before your workout. Protein would be the best thing to consume pre-workout along with some healthy fats or vegetables. If you consume a high carbohydrate or sugary drink during your workout you are blunting any growth hormone release from the exercise you are doing. Drinking these high carbohydrate drinks right after your workout will also kick yourself right out of the heightened fat burning state you worked so hard during your workout to attain. Eating another high quality protein with a healthy fat right after your workout will not thwart your post-exercise fat burning but will rather perpetuate the fat burning momentum generated by your workout.
Testosterone is the main hormone which creates the muscular and sexual differences between men and women. Enhancing your testosterone can have a dramatically beneficial effect on your physique, strength and sex drive. Even though women have less testosterone, they can still benefit as well to a lesser degree. Women will never get as muscular as men but the increase will simply will help them develop a shapely, toned figure.
Testosterone and dietary fat intake are very closely linked together. Eating a high fat diet, especially from monounsaturated and saturated fat sources causes a direct increase in testosterone levels, whereas polyunsaturated fat does not. Great sources of these fats to raise testosterone levels include raw nuts, olive oil, wild caught fatty fish, flaxseed and natural peanut butter.
What about testosterone levels in vegetarians? Since cholesterol is the building block of testosterone, it makes sense that eating a diet high in meat and cholesterol would yield much higher testosterone levels. If you are worried about eating foods higher in cholesterol, eating extra omega 3s, monounsaturated fatty acids and lots of vegetables will negate any possible negative effects. Typically a meat eating diet raises testosterone levels while a vegetarian diet decreases them and there is a 30 - 40% difference between the two groups. This could partly be because vegetarian diets often include soy which is linked to lower testosterone levels. Vegetarians will have a much harder time building muscle as a result, and the more muscle we have on our bodies the faster our metabolism will burn calories in a rested state. This makes it much harder for vegetarians to achieve an ideal body composition.
Many of the current dietary recommendations for people trying to lose weight such as limiting calories, trying a vegetarian diet and avoiding animal meats are a definite recipe for low testosterone. These diets are typically low in protein and usually high in carbohydrates, which would lead to suppressed growth hormone levels as well. Limiting total calories can also lead to a drop in testosterone which can hinder weight loss efforts. This is why you must be exercising so you will be able to consume additional calories while still losing weight and keeping your hormone levels elevated.
So although we are constantly bombarded with this anti-fat message, it turns out that diets too low in dietary fat are actually detrimental to testosterone levels. The ideal hormone optimization diet looks to be one that is moderate in carbohydrates (mainly low glycemic carbohydrates and vegetables), but limits their consumption pre and post workout and around bedtime. We should be eating moderate amounts of high quality protein (mainly coming from meats), and moderate to high in fat content (with an emphasis on monounsaturated fatty acids and omega 3 rich fats).