Can't Lose Weight? Are You Metabolically Flexible?

Health Writer

In March 2018 I covered the health status of President Trump and discussed MHO, metabolically healthy obesity, highlighting the fact that there seem to be individuals who have obesity and no signs of co-morbid disease. They may have some genetic protection, and some of them may engage in regular healthy habits but not to the degree that these behaviors would help with weight loss.

I suggested that this can just be a “healthy moment in time,” and there’s a likely risk of developing a host of diseases later-in-life. For most people diagnosed with obesity there doesn’t seem to be a free pass: you will likely suffer with other health conditions if obesity becomes a chronic, lifelong condition.

When assessing obesity risk, why do some people seem prone to gaining weight or have difficulty losing weight? One of the ways that clinicians and dieticians evaluate a person’s weight loss efforts is to have them keep a pristine food and exercise journal. If the journal entries suggests that the individual should have dropped weight, but didn’t, then one conclusion might be a lack of metabolic flexibility.

Metabolic flexibility means that your body is able to efficiently use sources of fuel which include fats or carbohydrates. So if you are metabolically flexible it means that your body can easily switch back and forth between these two fuels and efficiently burn them for use. It means you can enjoy a variety of food and will have little difficulty metabolically managing and utilizing energy from these foods.

If you are not metabolically flexible, on the other hand, you have a hard time burning fats or sugars for fuel and that can set you up for certain diseases, including obesity.

Inigo San Millan, a former pro cyclist and now researcher at Colorado University, Boulder, has spent years developing high-tech metabolic tests in order to assess the metabolic flexibility of professional athletes. Obviously, these individuals know that it’s critical to feed their body optimal fuel, and these types of tests help them to know which foods their body handles best.

In a best case scenario, an athlete wants to be able to burn both food fuel types efficiently. Millan is now bringing this technology to the public, offering people the ability to find out how they rank from a metabolic-disease perspective. He can then create a customized eating and exercise program to help optimize metabolic health and flexibility (efficiency). Not surprisingly, perhaps, he calls the process "metabolic rehabilitation."

The test format involves having a person come to his lab, get on a bike or treadmill, and begin to exercise while wearing a mask that measures how efficiently the person utilizes fat and carbohydrates during the exercise program. Resistance is increased during the test to see how the body reacts. Millan also takes blood samples to measure how quickly cells clear the lactate that builds up as the test intensity is increased. A buildup of lactate has the propensity to stiffen muscles and also to instigate disease.

But really what Millan is trying to capture is the health of the person’s cell mitochondria ― the power center of each muscle cell. Prior to this test format, the only way to get a true picture of mitochondrial function was to do a muscle biopsy, which is invasive. His test has shown pretty good accuracy.

Carbs have recently been maligned because they are high in sugar. Millan points out that many athletes handle a diet comprised of 70 to 80 percent carbs (high quality preferred) with no problem, likely because they are also metabolically flexible.

Is there another more accessible way to know if you are not a good match to sugar or fat as primary energy sources? Millan suggests that you see how you feel from a daily energy and weight standpoint. If you regularly feel “low energy,” and really struggle to lose weight and if you are developing increasing blood sugar levels, you may be metabolically inflexible. In that case, just starting an exercise program can help to prime mitochondria to behave more efficiently, a first step in better metabolic flexibility.

You may then need to test out some different diets ― one that possibly emphasizes high quality fat sources like oily fish, olive oil, nuts, avocadoes as primary fuel sources (version of Paleo) or a diet that emphasizes high quality carbohydrates like oatmeal, greens and fruits, and whole grains. Once metabolically flexible, you should be able to handle carbohydrates and fats more efficiently.

In 2008, a study looked at metabolic flexibility to see if it could be linked to insulin sensitivity, and specifically, insulin resistance. The study concluded that there was just not enough evidence to link mitochondrial defects to being a driving force in metabolic inflexibility and insulin resistance. More research was recommended.

Millan may be on to something, but I also think that most of us would see dramatic changes in energy levels and possibly better weight loss if we were eating most of our calories from whole, unprocessed foods and if we were clear on how many daily calories we should be consuming in order to achieve a weight loss of one to two pounds weekly.

Daily moderate to vigorous exercise will also enhance weight loss. Including resistance training will build more muscle mass (mitochondria). So although Millan offers his theory, we already know that this kind of diet and exercise program will likely reduce blood sugar levels and even reverse diabetes in some cases, especially if weight loss occurs.

Still, it does not surprise me that some people “struggle” with higher levels of carbohydrates or fats. It would seem reasonable that you may have a body that handles certain food groups better than others. Millan suggests that a more fit body and understanding how you personally respond to food will enhance metabolic flexibility and help with weight loss. He may be right.

See more helpful articles:

Smart Swap Outs for Sugar and Unhealthy Fats

Is There a Final Word on Saturated Fat and Heart Health

Portion Control: Fats, Grains and Treats