Denise stepped on the scales and looked down. The numbers between her toes were high, as they had been for 3 decades. Her weight was fine when she married, but raising three kids, juggling a career, and too many packaged meals for supper resulted in the pounds accumulating. However, there was a new emotion when she looked at the numbers. Fear. Denise had a lumpectomy 3 months earlier, and now the fear surged when she saw how many extra pounds she was carrying. She worried “Will my cancer return if I am so heavy?”
Dumping all the blame on Denise for her obesity is misguided. As we saw in the last post, she grew up in a system that is engineered to pack on the pounds. Food scientists from Harvard ran hundreds of experiments to find the exact combination of sugar, salt, and fat that would maximize people eating processed food.[i] They called it the ‘bliss point’, but such devious tweaking guaranteed overeating. Using cars and elevators and escalators to get everywhere kept us sedentary, and the pounds accumulating. The obesity rate tripled from the year Denise was born, until now.[ii] There is a toxic interplay of systems and profits and personal choices.
So how can we reverse the engineering? What is the intervention point that will give us the most benefit for our effort to reduce our risk of cancer due to obesity? After all, there is a stupefying amount of information swirling around, some of it totally contradictory. We were told that ‘low-fat’ was the way to go. Those products flooded the shelves of grocery stores. The obesity rate kept rising, because food companies loaded the ‘low-fat’ products with sugar in order to make them tasty. The solution wound up accelerating the problem. There is no end of new information to confuse the average person. Should we count macros? Go keto? Eat according to our blood type? Avoid gluten?
Thankfully, the research points to the lever, that if it is pulled, will give the greatest movement to reducing your risk of cancer. It comes from a summary of 31 studies which looked at the link between obesity and cancer.[iii] The table below shows the increase in risk of obesity-related cancers.
% increase in risk
Normal weight None
Overweight 10%
Obese 30%
The data is straightforward, the more excess weight a person carries, the higher their risk of obesity related cancer. But that is only half the story. Because the researchers looked at another variable, which is metabolic health.
Metabolically Healthy Metabolically Unhealthy (MU)
Normal weight None 11%
Overweight 10% 23%
Obese 30% 46%
Now, the story gets really interesting. We see that people who are metabolically unhealthy (MU) have much higher cancer rates than people who are metabolically healthy, even in the same weight class. The risk for cancer from being MU more than doubles for overweight people, and increases by 50% for obese people.
Clearly, this variable of being metabolically unhealthy has a major increase in your risk of cancer. So, what does being metabolically unhealthy mean? I must admit, I did not know either, until I stumbled on this research paper.
Good metabolic health is being responsive to insulin, while poor metabolic health is being insulin resistant. The largest cause of insulin resistance is the cells in the body being overloaded with too many calories.[iv] When you eat a meal, insulin is released to take the excess glucose into your cells. However, if your cells do not have room to store any more glucose or fat, then they become resistant to insulin. The excess calories become stored as fat, especially around the waist.
How do you transition from being metabolically unhealthy, to being metabolically healthy? It is not just about losing weight, because a normal weight person who is metabolically unhealthy has basically the same increase in cancer risk (11%) as someone who is overweight, but is metabolically healthy (10%). Instead, as the authors at the National Institutes of Health say “The benefits of exercise cannot be understated in treating patients with insulin resistance.” Yup, exercise is very powerful in improving your metabolic health. People in the upper third of cardio fitness are 10 times more likely to be metabolically healthy as people in the bottom third of cardio fitness.[v] [vi] That is a walloping difference.
If you pull on the lever of increasing your fitness level, then it will create the biggest movement in reducing your risk of cancer. After running a well-crafted study, experts concluded that exercise alone “may be nearly as effective as a more intensive multicomponent approach involving diet, exercise and weight loss” in improving your metabolic health.[vii] You will get the most bang for your buck if you just start moving your body.
This raises another question. How to move your body? Do you focus in cardio, or on lifting weights? The same researchers ran another study comparing aerobic training, to aerobic plus resistance training. They concluded “When weighing the time commitment versus health benefit, the data suggest that aerobic training alone was the most efficient mode of exercise for improving metabolic health.”[viii] Lifting weights is helpful, because it improves health generally. It also activates a different pathway in improving insulin management.[ix] But lifting weights alone does not move the needle in improving your metabolic health, the way that cardio training does.[x]
This sounds great. We have found the lever that gives you more benefit than improving your diet, losing weight, or resistance training. I am not saying to ignore these latter three things, as they are very good to do. After you set a foundation of aerobic exercise, you can then add the other changes of looking closely at what you eat, how much of it you eat, and resistance training.
Now that we found the most effective lever to pull, how hard do you have to pull on it? Do you have to be drenched in sweat after cycling for 40 minutes up a hill that includes a 15% grade, heart pounding at 165 beats per minute?[xi] Absolutely not. Nope. That is what people who are slightly crazy do. If you are sedentary and older, pushing yourself that hard results in less gains than if you set a more moderate pace.[xii]
Actually, being in the upper third of cardio fitness is something that ordinary people can achieve. You do NOT have to be an elite athlete. You just have to start walking. Seriously. One of the studies above found major improvement if people walked 14 miles in a week.[xiii] That is walking 10,000 steps a day, for 3 days in a week. In order to get to the upper third of cardio fitness, you have to jog for about 45 minutes, 3-4 times a week.[xiv] The path is very simple. Just walk at a brisk pace for an hour a day. As your body gets used to moving, then you can increase the pace by jogging. You can decrease the time you spend, because you have upped the intensity. You do not need to sprint, you do not need to race, you just have to move your body enough so that talking is a bit of a challenge. To really get the system effective, put it in the schedule. Having a routine where you exercise the same time, on the same days, greatly increases the chances of you sticking to it.
You now have a new system, engineered to reclaim your health from the influences that have eroded it over the years. Your fear of cancer will fade, as every step you walk or jog is dropping your risk of this dread disease. You will have greater energy, and confidence as well.
Dr. Eric Kuelker
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