So, you want to lose weight? You change your diet to cut those calories and start hitting the gym hard to burn off any extra! BUT you forget that as exhausted as you may feel after that killer 9am spin class, that has only actually burnt off a modest 300-400 calories.
There is something else that’s constantly burning off thousands of calories a day and we don’t even have to get a sweat on, and that’s your BMR or Basil Metabolic Rate… AKA your METABOLISM!
The BMR is responsible for 60-70% of the calories expended, through activities such as the beating of the heart, respiration, and body temperature maintenance. Here are some key factors that affect the BMR:
- Genetics. The one factor we can’t directly change. Some individuals have fast metabolisms, and some have slow metabolisms.
- Gender. Due to greater muscle mass and lower body fat percentage, men have a 10-15% faster BMR than women.
- Age. Because a younger person has a higher rate of cell division, once you are 20 years old, your BMR drops about 2% every 10 years.
- Weight. Due to increased body tissue volume, an obese individual actually has a higher metabolism than a thin person.
- Height. Tall thin people have a higher BMR than short people of equal weight. If both are on the same diet, the short person will gain much more fat.
- Body Fat %. A lower body fat % means a higher BMR.
- Diet. A strict diet or severe calorie restriction can reduce BMR by up to 30%. This is one of the reasons why people on a crash diet lose up to 10kg of water weight, then plateau.
- Body temperature. For every 0.5 degree increase in internal body temperature, the BMR increases approximately 7%. Physical activity significantly increases body temperature.
- External temperature. Prolonged exposure to extremely warm or very cold environments increases the BMR. People who live in these type of settings often have BMR’s that are 5-20% higher than those in other climates.
- Endocrine function. Thyroid glands that produce too much thyroxin can double the BMR, while BMR can drop by 30-40% in individuals with hypothyroidism, or inadequate thyroxin production.
- Exercise. In addition to increasing body temperature, exercise increases lean muscle mass, which burns more calories than fat – even when you’re not exercising.
How to work out your own BMR…