Photo by Ava Kitzi
Metabolism is one of the most important topics related to health and fitness. Numerous diets, workout routines and supplements claim to boost metabolism. Books are published and podcasts released every day with advice on the topic.
To understand all the buzz, it helps to understand what metabolism is and why it’s important. The simplest way to think of metabolism is to view it as the conversion of food to fuel. When we eat food, that food is broken down into nutrients. Macronutrients, like fats, carbs and proteins, are metabolized and converted into energy. We’re familiar with this energy being expressed as calories. Some energy is immediately used to fuel the body. The remaining calories are stored as mostly body fat or carbs called glycogen. When this energy is needed, metabolism kicks in again and those fats and carbs are used to fuel everything from breathing, to heartbeat, movement and every chemical process in the body.
This isn’t unique to humans either. Metabolism is essential for all life on Earth. Not many topics are more important than that. But this isn’t usually what we hear about metabolism. Most of the discussion is on weight loss. You’ve probably heard that weight gain is the result of slow metabolism or that weight loss comes from boosting metabolism. There is a nugget of truth here, but this significantly oversimplifies the importance of metabolism. I’ll come back to weight management later, but the crucial conversation revolves around metabolism for long-term health.
When metabolism isn’t functioning properly, there is a significant increase in disease. An unhealthy metabolism is associated with everything from diabetes and cardiovascular disease to dementia and even cancer. A condition called metabolic syndrome occurs when several metabolic systems go awry.
The result is increased body fat around the waist, high blood sugar, low HDL cholesterol, increased amounts of fat in the blood and high blood pressure. Physicians diagnose metabolic syndrome if three or more of these conditions are present. The difficulty is that most of these conditions don’t show symptoms. Regular monitoring and blood tests with your doctor, along with testing with an exercise physiologist are the best ways to stay informed of your metabolic risk.
Metabolic tests like Resting Metabolic Rate (RMR) and exercise metabolism (VO2) are great tools to assess your metabolic health and function.
Your RMR is the number of calories metabolized to keep you alive at rest. For a lot of folks, this is somewhere between 1,000 and 2,000 calories per day. It’s a big range, affected by several factors like height, weight, age, sex and individual genetics. Measuring RMR will tell you the exact calorie needs for your body. Similarly, VO2 is a snapshot of your metabolism, but only during exercise. Both tests involve measuring the oxygen and carbon dioxide you’re breathing, either at rest or while exercising. The result is a picture of your metabolic health, function and fitness. Perhaps one of the most important pieces of information gathered during VO2 testing is your metabolic efficiency (zone 2).
The aerobic zone that improves metabolic function the most is known as zone 2. This is an exercise zone where your effort is high enough to cause heavy breathing but low enough that you can still carry on a conversation. Research has shown that 1.5-3 hours per week of zone 2 exercise can prevent metabolic dysfunction, promote fat loss and improve several health risk factors. In addition to zone 2 training, muscle training is essential for a healthy metabolism. You’ve probably heard that lean muscle mass raises metabolism. While this is true, it’s a pretty small effect. More importantly, healthy muscle tissue is more sensitive to insulin, metabolizes fat and carbs more efficiently, absorbs more oxygen and helps to improve blood pressure. The ideal prescription for muscle health is two-three days per week of strength training. The best strength training routines focus on all aspects of muscular fitness. They start with muscle endurance, progress to building lean muscle mass, followed by increasing muscular strength and eventually improving the speed and power of muscle contraction. If your primary goal is metabolic health, shoot for two days of strength training per week, an hour each. On three more days, complete 30 minutes of zone 2 exercise like bike riding or speed walking. For more emphasis on fat loss and longevity, experienced exercisers can lift weights three days per week. Spend three more days doing an hour of zone 2. Your metabolism will thank you!
Mason Stevens is owner and clinical exercise physiologist at MET-Fitness in Columbia. He has his master’s in kinesiology and 20 years of experience in sports conditioning, health coaching and exercise physiology.