Chapter 1

How the Body Burns Fat

Obesity, or greater fat storage, usually results from a continuous imbalance between energy intake and energy expenditure. So, the key to fat loss is lowering energy intake and/or increasing energy expenditure—but it’s not only about calories in and calories out.

Fat burning is a very sophisticated and detailed biochemical process. This process is essential to your success with the six-pack diet plan. Knowing how the body burns fat and using that knowledge to your advantage is the essence of this program. Body metabolism and hormones play crucial roles in fat burning. To truly understand this complex topic, it is necessary to review how the body actually burns fat and uses it as fuel.

Fat as Fuel

Fat contains nine calories per gram, which makes it the most energy-dense macronutrient. Fatty acids are stored as triglycerides (three fatty acids and one glycerol unit) in adipose (fat) tissue. Burning one gram of fat for fuel provides more energy than burning a gram of carbohydrate or protein.

Fats are oxidized (burned) to provide energy through a process called beta-oxidation (or lipolysis). When blood sugar levels are low, especially during longer periods between meals, the hormone glucagon is secreted by the pancreas and this stimulates enzyme activity to release fatty acids from triglycerides. Epinephrine (adrenaline) can stimulate the same activity to release energy during the stress response.

Once they are released, these fatty acids travel through the blood to other body tissues, such as muscle, where they are oxidized to provide energy through the mitochondrial beta-oxidation pathway. The mitochondria are the “furnaces” in the cells of the body. Basically, fatty acids are converted to acetyl-CoA in this process and can then provide energy. Another destination of acetyl-CoA is the production of ketone bodies by the liver, which can then provide energy to tissues like the heart and brain.

This process may increase thermogenesis, the production of heat by metabolic processes leading to fat loss. Your metabolism is what keeps all the normal functions of your body active throughout the day and night—breathing, blood circulation, maintaining body temperature, digestion, and so on. By boosting the level of thermogenesis to accomplish all of these functions, you can burn off more fat.

Cardiovascular exercise can help mobilize fatty acid stores to be utilized as fuel. Moderate aerobic activity seems to burn more fat, although more intense cardiovascular exercise for the same duration may allow you to continue burning fat for several hours after exercise. The best time to do cardio is first thing in the morning on an empty stomach, drinking plenty of water and using a thermogenic supplement beforehand. This is when insulin levels are low and glucagon is higher, which helps prime the body for fat utilization.

The Importance of Brown Fat

There are different types of adipose tissue found in humans, including white adipose tissue (white fat), which is the majority of stored fat in the body. The other, more interesting type is brown adipose tissue (BAT), which actually burns calories by using up metabolic energy to create body heat. Brown fat contains large numbers of mitochondria to facilitate calorie burning. It is generally located deep in the body—down the spine and adjacent to the heart and kidneys.

One way to stimulate fat loss is by activating beta-adrenergic receptors—mainly beta-1 and beta-2 but also the beta-3 receptors show great potential for fat loss. Beta-3 agonists help target BAT, as these receptors are only found in fat tissue. Scientists have found that the beta-3 receptors are in high abundance in the thermogenic brown fat cells, especially within the abdominal region. It is theorized that stimulating the beta-3 receptors may help reduce abdominal fat.

BAT can also be found between the shoulder blades. So, the next time you do cardio, touch the area between your shoulder blades to feel the extra heat being produced. Many of the heat-producing effects of BAT are due to the expression of uncoupling protein-1 (UCP-1) gene. UCP-1 is exclusively found in the mitochondria of brown fat cells (white fat cells do not have mitochondria). You can think of UCP-1 as the light that ignites the fat-burning flame in fat cells. By finding ways to activate brown adipose tissue—activate the mitochondrial furnaces—body fat can be reduced.

Thermic Effect of Food

Another important factor affecting fat loss is the thermic effect of food. You might have noticed that after eating a large meal, you sometimes feel warm or even sweaty. This is due to the thermic (or heat-producing) effect of food. Whenever your body temperature is higher, you are burning more calories. Eating small meals frequently can actually be one way to boost your metabolism and burn more fat, because of this thermic effect.

But keep in mind that not all foods are created equal when it comes to the thermic effect. For example, calories from fat have almost no thermic effect. Your body can store fat very easily without using much energy, hence little or no thermic effect. However, protein is very difficult to convert to fat, so it has a very large thermic effect, as high as 30 percent. What this means is that if you eat 100 calories of protein, 30 calories will be burned just as heat so that your body can digest the protein. Other research indicates that a high-protein, low-fat meal boosts post-meal thermogenesis by 100 percent compared to a high-carbohydrate, low-fat meal. That’s why protein is an essential macronutrient in the six-pack diet, which optimizes the thermic effect of food to enhance metabolism and fat-burning day and night.

The Hormone Link

Many people complain that they just can’t lose weight, in spite of dieting, performing “lung-burning” cardio sessions, and taking handfuls of supplements. The solution may be inside you—it’s all about your own hormones. When trying to get as lean as possible and drop weight, you must consider ways to maximize your body’s natural hormones to impact fat burning. These powerful substances can mean the difference between a lean, fit body and a fat, unhealthy one.

Hormones are biologically active substances that regulate many key processes throughout the body. “Nothing can influence our body’s shape more than our own hormones,” says Karlis Ullis, M.D., noted hormone expert and author of The Hormone Revolution Weight Loss Plan. “Hormones regulate weight, metabolism, how much muscle we have, food intake, and many other factors.” There are some key hormones with regards to fat loss and muscle gain: the major players include growth hormone (GH), the sex hormones testosterone and estrogen, the thyroid hormones, insulin, and cortisol. “Without taking into account our hormones, and how we exercise, we predictably will regain all the weight we lost on some ‘crash diet’ plan,” states Dr. Ullis. By learning to optimize the effects of these key hormones, you can maximize your fitness routine and lose weight. Hormones can be powerful allies in your battle to achieve a great physique. The six-pack diet plan addresses each hormone and helps these hormones work synergistically in your fat-loss efforts.

Growth Hormone

Human growth hormone (GH) is the most abundant hormone produced by the pituitary gland. It is mainly released in pulses during sleep and GH secretion usually decreases with age. Most of growth hormone’s powerful effects are due to it’s conversion in the liver to IGF-1 (insulin-like growth factor type 1). IGF-1 is actually what is measured in a blood test to determine GH levels in the body.

Growth hormone has been shown to increase lean body mass, reduce body fat, increase energy, stimulate immune function, and even enhance sexual function. Obesity diminishes the release of GH and fasting actually helps increase it.

Because GH is released primarily during sleep, it is important to get sufficient amounts of sleep every night. Exercise, both cardiovascular and weight training, is a potent stimulus for GH release. Diet can also affect GH levels. For example, a study published in the Journal of Nutrition in 2002 showed that men consuming soy protein isolate (40 g daily) had increased levels of IGF-1. The six-pack diet plan helps you use growth hormone to stimulate fat loss.

Testosterone and Estrogen

Testosterone is a sex (steroid) hormone, produced by the testes and adrenal glands, that promotes the development of male sex characteristics and regulates male reproductive function. It is called the most powerful muscle-building hormone because it does just that—builds muscle and strength fast. Testosterone increases muscle protein synthesis and net muscle protein balance, resulting in increased muscle mass.

“Testosterone is one of the most effective hormones for burning fat in both men and women,” states Dr. Ullis. Signs of low testosterone levels include low energy, muscle weakness, depression, and sexual dysfunction. However, too much testosterone in males can also cause problems—it may convert into DHT (dihydrotestosterone), which can have adverse effects on the prostate and cause hair loss. It can also convert into estrogen, leading to water retention and increased fat storage.

Diet, particularly essential fatty acids, and certain types of weight training exercises can help boost testosterone levels.

It is important to measure both “free testosterone” levels (the active form) and estrogen levels in order to make sure there is not too much estrogen being produced. Estrogen can literally halt your muscle-building efforts. Estrogen is one of the body’s most powerful fat-storage hormones and higher estrogen levels in men can cause abdominal fat storage, bloating, and fatigue. Make sure you don’t have any mineral deficiencies, such as calcium or zinc, as this may be linked to high estrogen. Plus, drinking green tea and eating flaxseeds may help as well.

Thyroid Hormones

When people are trying to lose weight, they often experience a decrease in basal metabolic rate (BMR), which represents the number of calories that you burn at rest. This is especially true after long periods of low-calorie dieting, use of stimulants (including caffeine), and excessive amounts of physical activity. The body seems to reduce metabolism as a defense mechanism. That is why some of these people claim they cannot lose that last bit of fat.

The decrease in BMR is directly related to the level of thyroid hormones. Thyroid hormone activity is defined by the levels of two hormones released by the thyroid gland, thyroxine (T4) and triiodothyronine (T3). T4 is a low-activity hormone and T3 is a highly active thyroid hormone. T4 converts into T3 in the liver. Thyroid hormones are important for growth and development, as well as maintaining metabolism and normal body weight. Thyroid hormones also exert effects on thermogenesis and temperature regulation and can enhance lipolysis (fat burning) in adipose tissue.

To determine if your thyroid hormones are imbalanced, it is important to test T3 levels, since this is the active hormone. Diet, weight training, and nutritional therapy included in the six-pack diet plan can influence metabolism and the activity of the thyroid hormones.

Insulin

Insulin is a hormone produced in the beta cells of the pancreas. It is released due to a rise in blood sugar (glucose) levels in the body, which is induced mainly by eating carbohydrates. This hormone is primarily responsible for the direction of energy metabolism after eating. It can help transport key nutrients like glucose and amino acids into muscle cells, but it can also cause fat storage to occur.

Many people talk about controlling blood sugar levels and hence insulin levels to prevent fat storage, reduce cravings, and sustain energy levels. Other diets may have you eliminate carbohydrates altogether to minimize and control insulin levels. But can insulin really help you build more muscle mass or will it just cause more fat storage and halt your fat-loss goals? Insulin is a hormone that has been discussed heavily in the health and dieting communities. It is a vital hormone in the six-pack diet plan. It’s time to set the record straight and find out more about this intriguing hormone and the supplements that can help you positively manipulate it.

Insulin helps regulate blood sugar levels and helps keep them in the normal range. Normal fasting blood glucose levels should be 70-110 mg/dl. Individuals with type I diabetes cannot produce insulin, so insulin shots are necessary; in type II diabetes, they cannot use their insulin properly and may have insulin insensitivity. Insulin binds to specific receptors in cell membranes and helps drive glucose into the cells. Normally the cell membranes are impermeable to glucose, but when a cell receptor is activated, the membrane allows for a rapid entry of glucose into the cells. Insulin also helps activate glycogen synthase, an enzyme that helps make glycogen (the stored form of glucose) to be stored in muscle tissue and in the liver. Liver glycogen is mainly used to help keep blood sugar levels stable.

Insulin allows cell membranes to become more permeable to certain amino acids, creatine, and some minerals. Insulin causes glucose transport proteins (GLUT) to increase their activity allowing for increased glucose uptake by muscle cells during exercise. Two of these proteins are found in skeletal muscle: GLUT 1, which is present in low levels, and GLUT 4, which is responsible for the increase in glucose transport in response to insulin and muscle contractions.

It is believed that both insulin and exercise stimulate an increase of GLUT 4 transporters in the plasma membrane of skeletal muscle. Both exercise (muscle contraction, to be specific) and insulin stimulate an increase in glucose uptake by muscle. However, there is ample evidence suggesting that exercise during muscle recovery impedes glycogen synthesis. This is why I recommend that you refrain from any cardiovascular work right after resistance training—it may inhibit glycogen resynthesis and not let you recover from your weight-training session properly.

Although insulin helps dispose of blood glucose by storing it as glycogen, it can also convert the excess sugar into fat. Insulin is truly a double-edged sword because of this effect. What many people don’t know is that insulin supports amino acid uptake into muscle tissue as well, helping in the growth and recovery process. Enhancing glycogen levels in the muscle cells creates a more favorable environment for growth. It also causes cellular swelling (for every gram of glycogen stored in the muscle cell, there are 3 grams of water stored as well), which can have a hydrating effect on the muscle and create more stored energy to be used later.

Insulin’s opposing hormone is glucagon, which is activated when blood sugar levels are too low. This hormone can break down muscle tissue and reduce glycogen stores, so it is important to control it as well.

What and when you eat can have a profound effect on your insulin levels—the six-pack diet plan can help you maximize the utility of your insulin. A wide array of supplements are available to naturally balance blood sugar and insulin levels. Plus, some athletes report a better “pump” when using insulin-boosting supplements.

The Cortisol Factor

Most people have heard of cortisol and many know that it’s bad news. Unfortunately, they don’t know the extent of damage this hormone can cause, especially when they are trying to get lean abs. This muscle-wasting hormone is literally eating away at their fat-loss potential.

Cortisol is the primary glucocorticoid, a natural hormone produced by the adrenal glands (located atop the kidneys). Although cortisol’s precise actions are not completely understood, we know that it is essential for life. It is necessary to maintain important processes (heart rate, blood pressure, adrenaline release) in times of stress. Most of its effects are not directly responsible for the initiation of metabolic or circulatory processes, but it is necessary for their full response.

Normal kidney function also requires cortisol. When there is an absence or deficiency of cortisol, water cannot be excreted rapidly, which can consequently lead to water retention (this may also occur with too much cortisol). Controlling cortisol levels and thus lowering excess body water is one of the ways the six-pack diet plan can make you look leaner.

What Causes Excess Cortisol?

Any type of stress that occurs to the body signals the nervous system to relay this to the hypothalamus. The hypothalamus then responds by initiating the stress hormone cascade, starting with corticotrophin-releasing hormone (CRH), followed by adrenocorticotropic hormone (ACTH) release, and finally glucocorticoid production. Stress to the human body can include trauma, anxiety, infections, surgery, and even resistance training and aerobics.

Recent research has shown that elevated cortisol levels increased protein breakdown by 5-20 percent. Even mild elevations in blood cortisol can increase blood glucose concentration and protein catabolism (muscle breakdown) within a few hours in healthy individuals. Cortisol can also increase body fat levels, especially when it rises dramatically in the body.

Overtraining by athletes may cause higher cortisol levels, potentially leading to hypertension because cortisol causes sodium retention and potassium excretion. Excess cortisol causes insulin resistance by decreasing the rate at which insulin activates the glucose uptake system. Cortisol levels rise as you increase the amount of time devoted to intense exercise. In overtrained individuals, cortisol levels increase while testosterone levels decrease. That is why one measure of overtraining is the testosterone-cortisol ratio. Overtraining is defined as an increase in training volume and/or intensity of exercise leading to a decrease in performance.

The Unhealthy Effects of Cortisol

Cortisol reduces the utilization of amino acids for protein formation in muscle cells. A cortisol excess can lead to a progressive loss of protein, muscle weakness and atrophy, and loss of bone mass through increased calcium excretion and less calcium absorption. The major catabolic effects of cortisol involve facilitating the conversion of protein in muscles and connective tissue into glucose and glycogen (cortisol may increase liver glycogen). This involves both the increased degradation of protein already formed and the decreased synthesis of new protein. Cortisol can also decrease the utilization of glucose by cells through directly inhibiting glucose transport into the cells. A cortisol excess can lead to a decrease in insulin sensitivity and adversely affect tendon health.

Excess cortisol causes a redistribution of body fat to occur through an unknown mechanism. Basically, the extremities lose fat and muscle while the trunk and face become fatter. Several studies have verified that high cortisol levels are directly linked with increased abdominal fat and can even cause binge eating (especially sweets). One study published in Obesity Research Journal clearly showed that men with higher levels of cortisol had greater abdominal fat deposits. Another study published in Psychoneuroendocrinology suggested that women with high stress levels (which increases cortisol) ate more calories and consumed a greater amount of sweet foods. This study linked high cortisol levels to binge eating in women. The scientists conducting the study concluded that this pattern could adversely impact body weight and health over the long run. Researchers from the University of California, San Francisco, in another study published in Psychosomatic Medicine, stated that “central fat distribution is related to greater psychological vulnerability to stress and cortisol reactivity.” So, if you want to get lean, especially in the abdominal area, you have to control cortisol levels.

Cortisol inhibits growth hormone levels by stimulating the release of somatostatin, a growth hormone antagonist. It may also reduce IGF-1 expression. IGF-1 is one of the most anabolic agents in the body and is the substance that is responsible for most of the positive effects of growth hormone.

Cortisol has other hormone-modifying effects. It can directly inhibit pituitary gonadotropin and TSH (thyroid-stimulating hormone). By doing so, cortisol can make the target tissues of sex steroids and growth factors resistant to these substances. It may also suppress an enzyme that converts the relatively inactive thyroid hormone T4 into the active form T3 (triiodothyronine). This can decrease the metabolic rate and make it harder to lose body fat.

Cortisol seems to play a role in various disease states. It is found in higher levels in diseases ranging from AIDS and multiple sclerosis to Alzheimer’s. Prolonged high levels of cortisol can throw the immune system into chaos and ravage the human body. A growing number of researchers believe that many of the worst, and least understood, diseases will soon be identified as caused by high cortisol, and subsequently treated with cortisol-reducing drugs or supplements.

The six-pack diet plan can help you control cortisol levels so that you can reduce body fat and build lean, strong muscles.

How the Six-Pack Diet Plan Helps Burn Fat

As you can see, fat burning is a very complex process, but the six-pack diet plan can help you use these myriad ways to your advantage. In the following chapters, we’ll explore diet, nutritional supplements, and training methods that can help you lose weight and get a defined physique. What you eat and the timing of meals can modify insulin and help speed up your metabolism. A number of supplements, training tips, and other strategies can increase fat burning and modify hormone levels. The six-pack diet plan works with your body’s natural processes to maximize weight loss and muscle building.

This article was excerpted from The Six-Pack Diet Plan (Basic Health, 2005) by Rehan Jalali. More detailed information can be found in the book. The Six-Pack Diet Plan ($14.95) is available at bookstores and health food stores nationwide.