My fitness tracker is telling me I must burn at least 600 calories during each Longevity Athletics training session this week to lose three pounds! Okay, let’s do this! Hold on there … unfortunately, it’s a little more complicated than that.
Let’s explore three reasons why daily activity tracking and exercise counts can be problematic.
1) Calorie-burn estimates are not precise.
The calorie burn figures you see in articles, online calculators and fitness trackers are based on averages with large margins for error. Popular methods include:
• Direct Calorimetry – Scientists use a hermetically sealed chamber to measure energy burned. It’s the most expensive method, and rarely used because of it. Margin of error: up to 3.3 percent.
• Indirect Calorimetry – Gas exchange measurements are taken to estimate energy expenditure. This is the preferred method behind all of the calorie burn estimates you see. Margin of error: up to 45 percent!
• Consumer Fitness Trackers – Most are off by about 30 percent for total daily calorie expenditure. For aerobic exercise, popular devices show error rate between 9 and 23 percent. One such device, the MyZone MZ3 Physical Activity Belt, used exclusively at Longevity Athletics, will provide the least amount of error with the accuracy of an EKG monitor.
2) Individuals burn calories uniquely and variably.
Many factors affect the true calories burned during exercise and rest, including:
• Genes – A single variation in what’s called the FTO gene can cause you to burn 160 fewer calories per day.
• Epigenetics – External factors affect how are genes are expressed. For example, in mice, when a mother eats more of a specific nutrient during pregnancy, her offspring burn 5 percent more calories a day. Human studies indicate similar outcomes.
• Sleep – Sleep deprivation for a single night has the potential to decrease calories burned that day by 5-20 percent.
3) What and how much you eat influences how many calories you’ll burn
For example, in response to overeating, your metabolism increases. However, some people’s metabolism will adapt and burn more that others’. In a laboratory setting, a group of individuals consumed 1,000 more calories than they needed per day for eight weeks, and at the end of the study some gained as little as 1 pound while others gained as much as 10 pounds.
You’ll burn more energy digesting some macronutrients than others. For example, by way of digestion, you’ll burn 20-30 percent more of total calories from protein, 5-10 percent from carbohydrates, and 0-3 percent from fats.
Tracking calorie intake and calorie output is unreliable. Until science comes up with a better way, lets keep it simple with committing to eating the right foods, in the right amounts, at the right times, while engaging in the World Health Organization’s recommended 150 minutes of vigorous-intensity aerobic physical activity per week.