Most studies that compare dieting alone to exercise alone show that dieting produces greater weight loss than exercise. Even so, it’s best to combine the two. Dieting alone is practically guaranteed to lead to rebound weight gain because it does nothing to boost your resting metabolism and can make you lose lean mass — which itself leads to a lower resting metabolic rate. When that happens, it takes an extraordinary amount of willpower to stick with the reduced number of calories required to maintain the new lower weight achieved through dieting. Most people don’t have that much willpower, and nearly all who lose weight by dieting alone gain it back and and then some, producing a 97 per cent recidivism rate.
Still, many are disappointed with the results they get when trying to lose fat through exercise. Some complain that it comes off agonisingly slowly, which leads to such behaviour as gross overtraining, a misguided cure that’s often worse than the disease. The question then arises: Why does exercise so often fail to produce acceptable fat-loss results? I’ve seen it graphically illustrated at Gold’s Gym in Venice, California, my training base. There I’ve observed clients of personal trainers whose bodies never seem to change or improve in any way. Fat people remain fat, even when training under the guidance of a knowledgeable and experienced trainer. One obvious answer is that the clients don’t follow a proper diet, believing that the gym work is all they need. In other cases, more insidious problems may be at work.
1) The intensity factor. To be effective for losing body fat, exercise needs to be done frequently enough and with enough intensity to use up stored body fat. Resting too long between sets or gabbing interminably on cell phones is a good way to blunt exercise-induced fat loss — yet you see that going on all the time.
2) Pre-workout insulin surge. Another possible monkey wrench is eating high-glycemic-index, or simple, carbs before and during exercise. High-glycemic carbs enter the blood rapidly and trigger significant insulin release, and the insulin, in turn, blunts fat mobilisation during exercise. If you take in carbs during training, you won’t burn fat at all. Even getting too much protein prior to training can provoke a sufficient insulin response to inhibit fat use during exercise in those who carry more body fat.
3) Pre-workout fasting. Conversely, fasting, or not eating anything, before exercise lowers the respiratory quotient. That means you burn less fat during training when you don’t eat. The one exception is when you exercise the first thing in the morning on a completely empty stomach. The reduced glycogen stores at that time cause your body to rely on stored body fat for energy.
4) Frequent weight gain and loss. Engaging in yo-yo, or intermittent, dieting can also hamper exercise-induced fat loss. That will no doubt come as a surprise to many competitive bodybuilders, who habitually gain and then lose weight prior to a contest; however, it’s a classic example of yo-yo dieting. Studies with mice show that when the rodents lose a significant amount of weight after eating a low-calorie diet, they take twice as long to lose weight when they go back on the diet. In addition, compared to the first dieting phase, they take half as much time to put the lost weight back on when they start eating normally.
Studies with human subjects show that habitual yo-yo dieters end up fatter. Even worse, diet cycling predisposes a person to a higher incidence of cardiovascular disease than what fat people who stay fat experience. Those who overly restrict calories lose equal amounts of fat and muscle, but their eventual weight regain will be all fat, making it harder to lose fat the next time due to a metabolic slowdown from muscle loss.
5) Not enough sleep. Sleep is an often overlooked factor. Those who sleep less tend to be fatter for a number of reasons, chiefly an imbalance of gut hormones that affect appetite. One such hormone, ghrelin, is a potent appetite booster, while another, leptin, decreases appetite. One study found that those who slept only five hours a night had 15 per cent higher ghrelin counts and 15 per cent lower leptin counts than those who slept eight hours a night.
Lack of sleep also blunts insulin sensitivity, to the point where it can bring on latent diabetes. Not getting enough sleep boosts cortisol, which has catabolic effects on muscle. Cortisol aids the activity of lipoprotein lipase, an enzyme that encourages the body to store fat. Training too late or too hard before sleep may interfere with sleep and thus, paradoxically, counteract the otherwise beneficial effects of exercise on body fat loss.
6) Too much stress. Mental stress also boosts cortisol. Exercising when you’re under a lot of mental stress may inhibit fat loss due to stress-induced cortisol production. As suggested above, elevated cortisol often goes hand in glove with insulin resistance, further hampering fat loss through decreased fat use. As if that weren’t enough, elevated cortisol tends to depress leptin, increasing appetite and making dieting harder than it should be.
7) Depression. Mental depression is another form of stress linked to elevated cortisol. That can lead to diabetes, loss of muscle and elevated visceral fat, which is the deep-lying fat in the abdomen and is considered dangerous because of its direct link to diabetes, cardiovascular disease and cancer. Having a lot of visceral fat is strongly associated with tissue inflammation, which is extremely catabolic to muscle as well as the cornerstone of nearly all degenerative diseases.
Excess stress may also depress the release of hormones linked to lower body fat, such as growth hormone and testosterone, both of which counteract the effects of cortisol in the body. Elevated cortisol blocks their release. Lower testosterone is definitely linked to greater concentration of fat in the abdominal area, especially in men.
8) Being female. Women appear to have more trouble losing body fat through exercise than men. One reason is that they have a decreased sympathetic response — that is, they produce less of the catecholamines, such as epinephrine and norepinephrine, which help release fat from fat calls. If you have a lesser response during exercise, you experience a lower rate of fat burning.
Women also store fat differently than men. They have an easier time ridding themselves of upper-body than lower-body fat stores — a difference of hormone patterns. Women shouldn’t despair over the retention of lower-body fat but need to recognise that they won’t tap into lower-body fat stores until they’ve exhausted much of their upper-body fat.
In women, lower-body fat retention is characterised by a higher density of alpha-adrenergic fat-cell receptors. Women also have more fat just under the skin because of the higher concentration of estrogen in their bodies.
9) Low birth weight. Even your weight at birth can affect your fat-loss efforts. Low birth weight favours a later-in-life gain in body fat due to a preponderance of genes that encourage fat storage over fat burning. Being fat as a child and adolescent makes it tougher to lose fat as an adult because fat kids have larger and more numerous fat cells that stick around for life. On the other hand, if you possess’“cold-climate genes’, meaning that your ancestors came from a region of cold weather, you likely have a higher resting metabolic rate or even more brown adipose tissue stores, both of which favour greater fat-loss response to exercise.
10) The fat germ. One current controversy suggests that many fat people are infected with germs that provoke obesity. For example, a study of obese subjects found that 36 per cent of them were infected with a virus called adenovirus-36, which tends to encourage obesity by telling the body to develop new fat cells.
11) Mitochondria damage. Those with long-standing higher fat stores often have greater rates of internal oxidation. The portion of the cell undergoing the most oxidation even under normal conditions is the mitochondria, which is also where energy is produced and fat is burned. Long-term damage to mitochondria can result in impaired fat burning. Special thermogenic proteins called uncoupling proteins found in the mitochondria are key players. When mitochondria are damaged, the uncoupling proteins don’t function properly. Result: fat gain. Studies show that the obese often have smaller and less functional mitochondria, so they experience less effective fat burning and less efficient energy production and find it harder to exercise.
12) More fast-twitch fibres. Here’s one that bodybuilders won’t like. It involves the distribution of muscle fibre types in your body. Type 1 fibres, also known as slow-twitch fibres, favour endurance and fat burning. Type 2 fibres favour using glucose rather than fat as fuel and are far more friendly to muscle growth than type 1 fibres. Those who have a preponderance of type 1 fibres burn fat more easily during exercise than those who have more type 2 fibres. That explains why elite endurance athletes usually have a higher per centage of type 1 fibres; their increased fat-burning capacity and greater mitochondrial content favour increased endurance.
13) Low thyroid. While uncommon, low thyroid activity interferes with fat burning during exercise. The thyroid gland regulates resting metabolism, and thyroid hormones work with catecholamines to increase fat use. One problem with low-calorie dieting is that after a short time you hit a plateau and your weight-loss rate drops. Usually that means the hypothalamus in the brain has sensed the limited calorie intake and, to prevent tissue catabolism, downgraded the production and release of active thyroid hormone.
Increased overall body inflammation and elevated insulin have been linked to thyroid problems, and both are commonly found in those with a lot of body fat. The fat-induced increase in inflammation depresses the release of adiponectin, a beneficial fat-cell hormone that heightens insulin sensitivity and fat burning and depresses leptin resistance.
14) Toxins. The accumulation of environmental toxins has been linked to both obesity and failure to lose fat through exercise. Such toxins are fat-soluble and include pesticide residue on fruits and vegetables or in animal feed, and they are stored long term in body fat. They’re released when fat is mobilised, as occurs when you’re dieting or exercising, and their release inhibits fat loss. They might also interfere with thyroid activity or make you feel sick when you’re dieting, which dieters often attribute to the rigours of the diet itself rather than the actual cause.
Want more evidence-based information on exercise science, nutrition and food supplements, fat-loss, ergogenic aids, and anti-aging research? Check out Applied Metabolics Newsletter at www.appliedmetabolics.com.
Please share this article on facebook and help someone else.
©,2017 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited
