Published on June 27, 2018
The Great Debate
“Lose weight FAST,” “Drop 12 pant sizes in 7-days,” “Drop inches fast!” We’ve seen these featured headlines before, they’ve been commonplace in magazines, social media, and late night commercials for as long as we can remember. Companies have marketed quick and easy one-size-fits-all fixes to one of the most prevalent societal health issues, excess weight and obesity. Unfortunately, as appealing as these quick fixes are they tend to not offer much in the way of scientific backing. In opposition to this, today we get back to the science. We’ll explain the mechanisms of obesity, the role exercise plays in its demise and what type of exercise may be most beneficial to you.
The Body Keeps a Caloric Ledger
Our bodies are much like a financial ledger used to balance budgets. Internally, our cells strive to balance the books between our daily caloric intake and metabolic burn. When these calories are in surplus, our body stores it as fat in preparation for a “rainy day,” or when our ancestors may not have been able to easily find food. This is why when we diet and exercise to lose weight, we are fundamentally targeting our daily calories to go negative, reverse this ledger process and hence remove the fat. Of course, that is easier said than done because there is much more complexity influencing this balance. As we begin to understand the interplay and variability between the many players in our genetic makeup, exercise and diet type, we can better reach continued weight loss.
Health Effects of Obesity
Obesity’s designation as a public health epidemic should not be taken likely. A large body of evidence have pointed to obesity and physical inactivity as significant contributors to disease. Several chronic diseases such as hypertension, type-2 diabetes, metabolic syndrome, stroke, and coronary heart disease are all deeply rooted in obesity (1). Additionally, obesity affects a large set of seemingly unrelated diseases that range from breast and colon cancer to autoimmune conditions such as rheumatoid arthritis. Fat deposition is most dangerous when the mass is deposited in the upper torso (belly fat) and around organs (visceral fat). These fat deposits are thought to contribute to low-grade inflammation, insulin resistance, increased triglycerides and impaired metabolism, a common thread to many of these chronic diseases (2). Therefore, the most health beneficial exercise isn’t one to simply target weight loss, it’s one to specifically target visceral and abdominal fat mass loss (3).
The Fat-Fighting Mechanics of Exercise
As you’re probably well aware, exercise comes in many different flavors. There is the traditional separation between aerobic “cardio” exercises and anaerobic resistance “weights” exercise. They can also be typed between low-impact like walking and cycling or high-impact such as running and calisthenics. Finally exercises are characterized by different intensities (high, medium and low) that are a measure of how much energy is expended over a given period of time.
The bulk of recent literature has pointed to high-intensity sprint interval training as the most beneficial method to counter the ill effects of obesity. These exercises require you do to short bursts of high energy workouts between short periods of rest. Studies have found this method to be effective and quick acting in reducing dangerous visceral fat. The mechanics behind this are a little more complex than traditional calorie burning exercise. These pulsatile exercises increase several hormones in the body including catecholamines, cortisol and growth hormone. Following a workout circulating catecholamines, which include epinephrine and norepinephrine, increase by 6.3-fold and 14.5-fold respectively. These molecules drive direct breakdown of fat and target anti-inflammation (4). Growth hormone also increases about 10-fold from baseline and it works to modulate metabolism and alter your body composition to decrease total fat mass, especially abdominal fat mass (5). Finally direct studies analyzing cardiovascular risks saw that in 6-12 weeks there were significant improvements to lower measures such as blood pressure, waist circumference (a measure of belly fat) and blood glucose (6).
Medium-intensity continuous training, which is the traditional form of endurance training, is characterized by longer interval training with no rest periods, often long-distance running and cycling. In a meta-analysis, researchers found no difference in body composition improvements and visceral fat loss when compared to high-intensity exercises (7). However they also found that there was no loss in fat mass with those who did cycling training, possibly due to their low-impact nature. This and other studies have noted that medium-intensity still requires longer time-commitment of about 40% more exercise per week than high-intensity training exercise (7-8).
There is a clear correlation between the amount and intensity of exercise and the results you can achieve. This may come across as an obvious finding, but it may be surprising to see how short high-intensity workouts can be just as good, if not better than your standard long-term endurance training. It just goes to show that the more work you put in the more you’ll get out.
But Wait There’s More...
Exercise still may yet have a few more surprises up its sleeve. Beyond the fat and calorie burning ability, studies are beginning to find several more mechanisms certain exercises can provide in combating obesity. One major pathological component that obesity imparts to chronic disease risks is inflammation mediated by an increased release of pro-inflammatory messengers called cytokines from fat cell adipocytes (10). One study found that one of these cytokines, TNF, is decreased with only 20-minutes of moderate exercise (11). Other studies have found increased anti-inflammatory effects of other cytokines such as interleukin-10 and ultimately decreased baseline inflammation from decreased adipocytes (12).
Another interesting benefit is that long-term exercise has been found to alter our genetic expression through changes in our epigenetics. Although still an area of active research, studies have found evidence for epigenetic changes giving us a plethora of beneficial improvements to cognitive function, muscle gene expression, and cancer protection (13). More excitingly it is even thought that some of these changes are able to pass onto your children through what researchers call ‘transgenerational epigenetic inheritance’ Although it’s best that we save that discussion for another day.
We get it, unless you’re one of the few who enjoy it, exercise can be tough. It’s difficult, hot, sweaty, and painful. Believe me, we get it. But if you can power through, the results will speak for themselves. There is no one exercise plan that will work for everyone. Choosing what fits and what continues to work for you is key which is why for many working with a physician, trainer and/or dietitian can be the key to success.
From the literature, high-intensity interval training via sprinting provided the most studied benefits to losing visceral fat mass in the quickest time but it may not be feasible for some due to the namesake periods of full intensity. The mainstay medium-intensity aerobic exercises are also good for visceral fat loss but can be slower and more dependent on sustaining your exercise volume over longer periods of time. Low impact and low-intensity training could could also be great additions to an aerobic workout regimen as they still reduce the periods of no activity. Finally all exercise regimens showed best results, especially with weight loss, only when combined with a nutrient-dense wholesome diet (14).
Whatever you decide, the most important factor is whether or not you can sustain it. Don’t be attracted to the claimed easy fixes, it’ll take work but it’s worth it.
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Mendelson M, Michallet AS, Monneret D, Perrin C, et al. Impact of exercise training without caloric restriction on inflammation, insulin resistance and visceral fat matt in obese adolescents. Pediatr Obes. 2015; 10(4): 311-319.
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