Resting Metabolic Rate (RMR)

Long-term rapid weight loss programs can have a profoundly negative effect on your resting metabolism. The resting metabolic rate is the total calorie requirement of the body over a period of 24 hours in order to maintain all functions at rest, including vital organ functions, maintaining body temperature, thought processes and breathing. In 1993 researcher examined 328 healthy men (17–80 years) and 194 women (18–81 years) volunteers who were characterized with regard to RMR, body composition, physical activity, maximum oxygen consumption (maximum VO2), anthropometry and energy intake. The measured RMR was 23% higher in men with around 1750 kcal / day than in women with around 1350 kcal / day. Your resting metabolism, another term for RMR, depends on your height, age, muscle mass, and climate. In warmer climates, the rate is lower because you need to use less energy to maintain your body temperature.

If you can’t get into a colder climate to alter your RMR, you can increase resting energy expenditure by being more physically active and increasing muscle mass. With more muscle mass, you burn more a day at rest. How many you ask A change of just 100 calories can theoretically equate to 36,500 calories per year, or about 10 pounds of body fat [1]

Of course, you can also reduce your RMR by adopting a sedentary lifestyle, losing muscle mass, or making excessive calorie restrictions. That’s right, if you are lowering your calories, such as dieting, you can lower your RMR and make your diet less efficient.

Decreasing your resting metabolic rate is a natural protective mechanism of the brain to prevent it from being interpreted as insufficient calories to maintain vital organ function and all related physiological functions that occur 24 hours a day, seven days a week. Let me give you an example. While running a movement physiology laboratory, I had the opportunity to measure the RMR on two of our employees. Both of them had decided to go on a weight loss program of 800 calories a day offered by a local endocrinologist because of their obesity. Before starting their 800 calorie diet, they both fell within the normal 1,200 to 1,300 range. One month after she lost weight, her RMRs dropped to around 950-1,000 calories per day. This 200 to 300 calorie reduction in RMR is the equivalent of a 20 to 30 pound burn Fewer Body fat over a year at rest.

The decrease in resting metabolism in the face of “decrease in caloric intake” is a major problem that is overlooked by most consumers. This is a major reason why most who follow rapid weight loss programs will regain weight faster the second time around and it will become increasingly difficult to lose significant fat mass in the future. The combination of an now unusually low RMR with the combined limited exercise ability makes the task of losing excessive fat mass extremely difficult.

Many weight loss programs use different equations to predict the RMR. However, studies have shown that these equations are often inaccurate, misleading participants, and significantly affecting their long-term success. One study reported an overestimation of the RMR of around 10% for men, 15% for women, and possibly even 20–30% for other demographics. Another concluded that equations predicting an RMR within 10% of an actual reading were accurate only about 40% of the time, regardless of gender and weight classification. The authors concluded that “direct RMR measurements should be taken wherever possible in clinical weight management settings”. Most recently in 2017 Researcher reaffirmed that, compared to directly measured RMR prediction equations, resting metabolic rates and energy requirements are overestimated by 10% to 30%, depending on the equation. Therefore, without direct measurement, many overweight people can greatly overestimate their calorie requirements both at rest and during exercise, as already mentioned previouslydiscourage their efforts to successfully lose or manage their weight.

The takeaway items are as follows:

  • Long-term success in weight loss and control involves effort, pain, difficulty, and time. There are no long-term successful links as announced.
  • You need a basic amount of calories per day for normal resting physiological processes to function normally. Calorie values ​​that are kept below these values ​​trigger a physiological adaptation in “starvation mode”, which hinders both short-term and long-term success in weight control.
  • For most, expecting more than 1 to 2 pounds a week in actual fat mass loss is unrealistic. All that is greater is the weight of the water.
  • The calorie requirement at rest and during training increases with improved physical condition.

This article highlighted the dangers associated with underestimating the basic need for resting calories in order to lose unwanted body fat. In the next part of this series, I’ll highlight how overestimating your exercise calorie needs also hinders your weight control efforts and the significant differences between healthy and non-healthy individuals.

[1] The usual calculation is that there are 3,500 calories in one pound of body fat