Carla Prado, left, prepares a client for a body composition test.


You Can Be Overweight and Too Lean at the Same Time

Jump into the Bod Pod to find out what you're made of

By Therese Kehler

January 16, 2019 •

The door closed. Swoosh. The magnets locked into place. Thunk. A humming filled the chamber and my ears adjusted to the changing air pressure. I was in a machine, which looked like something from science fiction, to test my body composition. But the U of A's Human Nutrition Research Unit uses science - and specialized equipment like that "Bod Pod" - to understand what we're made of, how much energy we use and, most importantly, how we can stay strong for the long haul.

Led by Carla Prado, a researcher, registered dietitian and associate professor at the Faculty of Agricultural Life & Environmental Sciences, the research unit has made some groundbreaking health discoveries. But it's not just for researchers and, shortly after it opened its doors to the public last year, I visited the research unit for a health assessment.

Before stepping into the Bod Pod, I changed into compression shorts and tank top and tucked my hair underneath a bathing cap. The pod would measure how much space my body occupied inside the capsule. Without a bathing cap to restrict it, the machine could register a full head of hair as fatty tissue.

The test itself was painless and brief. It took about 45 seconds and repeated for a second reading. (Prado said a third scan is sometimes needed if the first two results are inconsistent.)

The results showed my fat mass to be 20.1 per cent, slightly lower than the healthy percentage. In practical terms, the test gave me another health statistic that, along with the more familiar blood pressure and heart rate, I could use to benchmark against changes in nutrition or exercise.

But where does a Bod Pod measurement fall in a health assessment? It's one of three important aspects of health that Prado's team researches: body composition, energy metabolism and nutrition. Taken separately, these fields of study aren't new. What makes the research unit at U of A one of the best in Canada is that it's a "one-stop shop," combining these assessments under one roof and analyzing the impacts of each one on the others, explained unit research co-ordinator Stephanie Ramage, '08BSc Nutr/Fd Sci, '11 MSc, RD.

1: Body composition is the amount of fat and non-fat mass in the body.

The number on the scale doesn't tell you much about your body composition. Two people can weigh the same but have huge variations in the ratio of fat and lean mass - and that can have a big impact on health, Prado said. (Simply put, lean mass is total body weight minus body fat.) Prado showed me a picture of three identically shaped bodies-but they had radically different fat-to-lean mass ratios. When lean mass falls dangerously low, it can affect a person's ability to move, to function independently and to fight disease.

Let's be clear: fat isn't bad. A person needs a certain amount of body fat to protect internal organs, provide energy and regulate hormones. For women, about 23 to 30 per cent is healthy; for men, it's 13 to 20 per cent.

The problem comes when the amount of lean mass drops below a healthy threshold. "The idea that we have of low lean mass is of someone who is very petite, flesh and bone," Prado told me. "But in cancer or in a lot of chronic conditions, 50 per cent of people with normal body weight have low lean mass."

A body with low lean mass is less able to cope with chronic diseases. This was a key discovery in Prado's 2008 research, which compared cancer patients who had obesity yet also had extremely low lean mass (a condition called sarcopenic obesity) to patients who had obesity and normal lean mass. The conclusion was startling: "Independent of the stage of cancer that they have," she said, "they will die faster if they have low lean mass."

2: Energy metabolism is the amount of energy, or calories, your body needs over the course of a day.

With an estimated 25 million active Fitbit users, it's clear that people are fascinated with how many steps they take every day and how many calories they burn. In the nutrition world, it's called energy metabolism.

"We need energy just to keep our hearts beating and our lungs breathing," Ramage said. We burn more than half our calories doing nothing more than lying down - but that resting metabolism can differ by hundreds of calories between a highly trained athlete and a sedentary person.

Knowing your body's rate of metabolism is key to devising a plan to reach your health goals. The nutrition lab has two ways to measure metabolism. One of these is the Whole Body Calorimetry Unit - the best metabolic test there is. It can tell you how many calories you're burning, and it can see whether those calories come from fat or carbohydrates. They are both fuel for your body. Carbs are from the glucose in your bloodstream and the glycogen in your muscles and liver. Fats are the laid-away energy stores in your body that help fuel you when you need energy beyond what the more readily available glucose and glycogen can provide.

3: Nutrition is the effect of food on the body, in this case carefully calibrated meals prepared by a research kitchen.

A primary research focus of the unit is food: the impact of nutrition and diet on the body, particularly in people with cancer and other chronic diseases. The lab looks at three "macro" sources of calories. Carbohydrates come from the energy-providing grains, fruits, veggies. Proteins are the muscle-building meat and meat substitutes. Fats are the vital nutrients from fatty fish, nuts and oils.

Researchers will tweak meals and measure the results, Prado explained. "Can you burn more fat if I give you a lower-fat diet? Or can you burn more fat if I give you a low-carb diet?"

Prado said she'd like to see these types of assessments take place in hospitals as a matter of course to help predict who is at risk of low lean mass and design nutrition plans to prevent it.

Open to the public

The unit's primary focus is research but, for a fee, it offers three types of tests to the public. Feedback from a pilot project was positive, Stephanie Ramage said. "I think people were excited to see the real numbers and be able to take that back to their dietitian and come up with a solid plan."

Bod Pod Body Composition Assessment: At $100 and 30 minutes, it's a useful test to see your starting point before beginning a diet or fitness regimen and want to check your progress with future assessments.

Whole Body Calorimetry Unit: At $175 and 60 minutes, the "hotel room" unit analyses your energy metabolism, assessing how many calories you burn in a day based on your resting metabolic rate so you can work with a dietitian to create personalized meal plans.

Metabolic Cart Energy Metabolism Analysis: At $100 and 30 minutes, this test is slightly less accurate than the calorimetry unit, but still provides significantly better results than an activity tracker or calorie calculator.

Prices don't include GST

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