- Monique Vuong, MS, RD
WEIGHT LOSS AND METABOLISM --- THE PARADOX
Updated: Jan 17, 2022
Have you ever wondered how you can exercise and cut calories, yet fail to lose weight? Or perhaps put on even more weight than where you started?
So often I hear friends and strangers tell me, "I am exercising a lot, eating 'right', and I'm not making much progress." Typical scenario: a person exercises, reduces caloric intake, loses some weight, but then the weight loss stalls (even while maintaining diet and exercise regimen), and slowly creeps back up.
Well let me tell you -- the problem lies in excessive focus on calorie restriction to lower a number on the scale, rather than on body composition. A few weeks ago, I attended the annual Food and Nutrition Conference and Expo for dietitians and healthcare professionals, and there was one specific talk that addressed this precise concern. Weight loss alone is a poor determinant of health and progress. The traditional view of weight loss suggests that creating an overall calorie deficit will result in shedding of pounds. It is typically advised in the medical community that individuals cut back daily caloric intake by 500 calories/day to achieve a reasonable weight loss goal of 1 pound a week. (Note: A pound of fat is equivalent to 3500 calories.) This is the message that gets spread day in and day out, so this is how we are used to measuring progress.
What if we focused less on a goal number and more on fueling to maintain and build lean muscle mass? An individual's metabolism, or Total Daily Energy Expenditure (TDEE), reflects his/her ability to burn calories and is influenced by a number of factors:
1) Resting Metabolic Rate, RMR (~70%)
2) Non-Exercise Activity Thermogenesis, NEAT (~15%)
3) Thermic Effect of Food, TEF (~10%)
4) Exercise Activity Thermogenesis, EAT (~5%)
Of all these factors, Resting Metabolic Rate is the greatest component of metabolism, accounting for ~70% of TDEE. And what do you think is a huge contributor to one's RMR? Muscle mass (also referred to as Fat Free Mass, FFM)! For those who are not familiar with RMR, it is the bare bones minimum amount of calories our bodies require to function and preserve muscle mass at rest. Any less than 1300 calories/day for women and 1700 calories/day for men is not recommended! If we eat below what is required of our RMR, we will burn fat, but we also start to compromise our body's ability to function effectively and break down existing muscle. This, in turn, lowers our RMR and slows down metabolism, leading to greater weight gain. See the counterproductive nature of excessive restriction in calories?
Add in an exercise regimen, and energy needs actually go up, particularly if you are doing resistance training and weight-lifting. This form of exercise requires specific amounts of carbohydrates and protein pre- and post-workout to fuel as well as to repair and build muscle. Your efforts are wasted if you are putting all this time in the gym, yet you're not giving your body the building blocks to maintain and build muscle. Greater muscle mass, in turn, will raise your metabolism and the number of calories you burn in a day.
Some people may ask, well what about fat loss? Yes, it is necessary to create a calorie deficit to lose fat, however, being too restrictive (reducing any more than 500 calories/day) may also make you lose muscle in the process. It is important to set reasonable goals and focus on fueling for muscle with nutrient-dense foods. Creating a calorie deficit by way of raising metabolism helps with fat loss without compromising muscle mass. Notice the shift in mindset?
This leads me to my next point -- what about the number on the scale? After taking all these steps to maintain and build muscle, you may notice that the number on the scale may not be what you expect, even with the calorie deficit. This is because muscle weighs more than fat. Your body composition is changing, but this number is not reflected in the scale. This is why focusing too heavily on your weight can be a detriment to long-term goals.
What is the takeaway message?
Stay away from overly restrictive regimens, particularly ones that go below RMR (on *average*, 1300 calories/day for women and 1700 calories/day for men). Our bodies need fuel to function properly. (For those that are interested in knowing their RMR, the gold standard for measurement of body composition and RMR is the DEXA scan, which is offered at various health centers.)
Incorporate resistance exercise with proper fueling measures to build muscle and raise RMR which, in turn, speeds up metabolism. (Aerobic exercise alone does create a calorie deficit, but does not help with raising RMR.)
Don't rely too heavily on your weight as a gauge of attaining your goals. Factors such as decrease in waist circumference and increase in energy/physical strength are more telling of progress.
I'll leave you with those thoughts for now and save pre- and post-workout fuel for my next post. Until then, fuel for your muscle needs!