Carbs not the enemy: CU Boulder physiologist shares key to weight loss, metabolic health
Inigo San Millan has good news and bad news for those determined to make this the year they get healthy and shed some pounds: carbs are not the enemy, but you and your well-worn couch need some time apart.
The physiologist and University of Colorado director of the Sports Performance Program's research found success in weight loss and fending off cardio-metabolic diseases lies in metabolic flexibility.
"Metabolic flexibility is the ability for your body to quickly switch back and forth between fat and carbs, efficiently using whatever fuel sources you throw at it," San Millan said.
This kind of flexibility doesn't hinge on an ability to touch your toes, but on the state of your mitochondria. A flashback to high school biology should recall mitochondria as the powerhouse of the cell, responsible for burning through fat, carbohydrates and lactate.
"As we become sedentary and physically inactive, our mitochondria become atrophied or dysfunctional, and they start losing the ability to burn glucose and fat," San Millan said. "That's when we become metabolically inflexible."
General symptoms of metabolic inflexibility include: sluggishness, trouble losing weight regardless of dietary changes and increased blood sugar levels.
For a more accurate diagnosis, San Millan developed a non-invasive method of assessing the mitochondria's performance he initially used to gauge the metabolic flexibility of athletes. The physiologist now uses a streamlined version of the test — "metabolic rehabilitation" — for the general public involving a brisk treadmill walk or stationary bike ride while wearing a mask that measures how efficiently the subject utilizes fat and carbohydrates.
By 2018, San Millan said the test will be covered by some insurance companies.
"We want to bring this to the masses," San Millan said. "The ultimate goal is to have a more science-based diagnosis across many clinical settings of the methodology I use that is not just utilized as a diagnosis but also used for a prescription of exercise."
The exercise is key, San Millan said.
"There's a misconception out there that people believe the only way to exercise is high intensity," San Millan said. "We know that's totally wrong. It's not sustainable. The main thing in an exercise program is to create sustainability."
San Millan suggests low-intensity aerobic activity, endorsing something as simple as walking for one hour a day, four to five days a week.
"Our society has become more and more sedentary in the last 20 years or so," San Millan said. "The food isn't the problem. It's the lack of physical activity. Sixty minutes of activity used to be nothing when we were kids. You were lazy if you only moved for an hour a day. Now, that's a major goal."
Liz Wolfert is a believer.
The 34-year-old Denver resident found out she was pre-diabetic and discovered San Millan and his metabolic rehabilitation in 2016 through the urging of her mother.
Wolfert and her mother signed themselves up for the test.
"Her metabolism was in the range of a good, healthy metabolism, and mine was not," Wolfert said. "That was a huge shock."
Wolfert was no stranger to exercise. She'd climbed fourteeners, cycled, swam and done Kung-Fu, but her regimen wasn't consistent.
San Millan prescribed walking for about one hour a day. When Wolfert returned a year later to get tested again, she did not have any indicators of early diabetes.
"It's so interesting," Wolfert said. "I had climbed fourteeners before, but I remember how hard it was. After I started walking more, I climbed another one, and it was so much easier. It was like my body was working so much more efficiently. I started to run, and it wasn't an excruciating process. My body has just been better primed."
Wolfert said she spreads the news of a low-intensity aerobic workout to her friends.
"The beautiful heart of the advice is that it doesn't have to be this big, complicated thing," Wolfert said. "Yes, it would be great if you could run 5K's and do fourteeners, but you will get much healthier and potentially avoid diabetes just by walking. Just walking!"