As a physical therapist, I am numb to hearing diet and exercise in the same sentence, but I still cringe a little bit. The fact is that diet and exercise are not the same: Diets refer to the external sources of energy that fuel metabolic processes while exercise is a metabolic action of skeletal muscle. In the same way that the liver is an organ, the skeletal muscle is not only the biggest organ in the body, but also the biggest metabolic organ. While it sounds ridiculous to associate diets and the liver with weight loss in the same sentence, we have no problem equating movement, one of the many functions of the skeletal muscle with weight loss.
This fundamental misunderstanding of metabolism assumes that there is some extra energy lying around that can be used through exercise to raise the daily energy requirement and burn off the unwanted fat by choice. Therefore, when we run, jog, or walk, we certainly feel good and mistakenly anticipate that breaking the sweats along with huffing and puffing of exercise session would almost translate to instant weight loss, and some would not hesitate to step on the weighing scale immediately after a bout of exercise. If this were so, we would all be skinny.
Before industrialization, sickness and death were mainly caused by infectious diseases. Besides, of all the body organs, the skeletal muscle is the only organ we can voluntarily move and therefore it does not appear that movement is part of physiological processes that has anything to do with illness and health. Arguably, this is not an intentional view because most of the metabolic processes are performed without any awareness and therefore very easy to divorce exercise from overall metabolism. This is why most people put off exercise to some days in the future because there is no such thing as “muscle attack” with sedentary living but everyone hopes and prays that their heart muscle never stops. The fact of the matter is that exercise is a huge part of metabolism and not a tool for weight loss.
In the 1950s, at the beginning of industrialization, when the middle age population in the workforce were dropping like flies from heart attacks, doctors could not find germs to treat and it took a long time to reach a consensus that sedentary occupation was associated with heart ill-health. Couple of decades before the heart attack epidemic, the doctors could not explain the cause of hypertension which also set off controversy about whether to treat hypertension or not. The eminent cardiologists of the day who were on the side of “do not treat” were Drs. Paul Dudley White and J. H. Hay. Dr. White was quoted as saying “hypertension may be an important compensatory mechanism which should not be tampered with, even were it certain that we could control it”. Dr. Hay was not so subtle and derided his colleagues by saying “the greatest danger to a man with blood pressure lies in its discovery, because then some fool is certain to try and reduce it”.
Before the modern calorie-rich-labor-saving environment, skeletal muscle via daily physical activity put the lid on chronic diseases. Given that man has always lived in persistent limited energy resources, each organ and system of the body has a pre-allocated energy per day and according to the recent constraint energy theory, long-standing physical inactivity triggers energy conflicts between multiple systems, especially between the brain and the immune cells and thus opens the floodgates to chronic diseases in several metabolic pathways. The contracting skeletal muscle drives all organs toward “oxidative phosphorylation” that improves the efficiency of the so-called Krebs cycle for the production of chemical energy called ATP, water, and carbon dioxide. Without the normal mechanical stress propagated by the contracting skeletal muscle on individual cells and systems, the energy given up by the skeletal muscle is stored as fats and appropriated by the selfish immune system.
Therefore, in the absence of infection, the immune system is unusually activated in a calorie-rich sedentary state through the “backdoor” pathways that block the self-regulation to end inflammation within 4-7 days. This energy hijack by the selfish immune system leads to weak but unresolved low grade chronic inflammation and has been attributed to be the “cause of causes” of most metabolic diseases or modern chronic diseases.
The protective health effect of chronic exercise is very obvious, but we tend to disregard it. It has been recorded that people in traditional societies eat more carbohydrates than people in the Western world but they hardly have diabetes, heart attacks and hypertension. And while they may die of infectious diseases before age fifteen, studies have shown that they live as long as people in the Western culture once they get past 15 years. For instance, Tsamine tribe has been recorded to have the best heart health on the planet with low blood pressure throughout adult life and no history of heart attacks. The question is how do they maintain good metabolic health into the old age? It appears this has to do with considerable duration of daily physical activity. While we run or jog on treadmills, and do brisk walking for 30 minutes or more, people in traditional societies just walk and hardly run except during fight or flight situations. In fact, running is so rare in traditional societies and to buttress this, an African proverb says, “If you see a man running in the bush full of thorns and spikes, if he is not pursuing something, something is definitely pursuing him”.
Furthermore, observation of the active Sumo wrestler has shown that exercise alone, not diet, is the prime driver of metabolic health. A search for top 10 Sumo wrestlers revealed an incredible weight range from 520 to 645 pounds. A typical sumo wrestler eats about 7, 000 to 10, 000 calories a day but participates in several hours of gruesome exercise from as early as 5 am till lunch time. Surprisingly, sumo wrestlers are known to be metabolically healthy during their active professional years despite their enormous consumption and weight. However, the health protection they enjoy during active wrestling years is lost and the chronic diseases related to obesity are activated once they retire and less active, even with drastic cut on consumption.
We talk about all kinds of diets to promote health but the big elephant in the room is the exercise part. In traditional societies with limited food availability, the duration of walking per day is more than 100 minutes. Also, the active sumo wrestlers, who eat up to 10,000 calories per day but participate in gruesome exercises of up to 4-7 hours on a daily basis. The only common thing about the hunter/gatherers and active sumo wrestlers is the long durations of physical activity which undoubtedly accounts for their good metabolic health. According to the World Health Organization, approximately 3.2 million people die every year due to physical inactivity. Decades of physical inactivity take a toll on health span in Western civilization and later years are often spent managing ill-health and grappling with progressive decline in quality of life. The prevalence of modern chronic diseases is not due to diets or obesity, it is driven by the exercise gap.
When it comes to metabolic health, exercise duration matters.
Mukaila Kareem, a doctor of physiotherapy and physical activity advocate, writes from the USA and can be reached through email@example.com