You may have heard the term "basal metabolic rate" before, but you're not quite sure what it actually means. Put simply, it's the amount of energy your body needs for its basic vital functions — keeping your heart beating, breathing, and maintaining body temperature. If you spent the whole day lying in bed doing absolutely nothing, the energy your body would burn is what we call your basal metabolic rate. In essence, it's the energy you need to survive, and it doesn't include the energy you use for everyday activities or exercise.
The link between basal metabolic rate and weight loss
If you're trying to lose weight and feel like you're eating next to nothing yet the scales won't budge, your basal metabolic rate may well be the answer. If you eat less than your basal metabolic rate, you will lose weight for a while — but once you return to normal eating, the yo-yo effect kicks in.
It's important for your daily calorie intake to sit somewhere between your basal metabolic rate and your total energy expenditure. In other words, you should eat at least as much as your metabolism needs to maintain its basic functions.
If you eat less than your basal metabolic rate, your body switches into survival mode. It slows down its metabolism and tries to conserve energy. On top of that, it starts storing more calories as fat because it fears further starvation. Your body is trying to keep you alive, and losing weight is simply not its priority at that moment. That's why strict diets — let alone fasting — are genuinely unsuitable for weight loss.
An exception may be people suffering from morbid obesity. In their case, calorie intake can be temporarily reduced below basal metabolic rate when rapid weight loss is needed, for example before a planned surgical procedure. However, such very-low-calorie diets must always be carried out under professional supervision!
How to find out your basal metabolic rate
If you want to know how much energy your body needs for its basal metabolism, there are several ways to find out. You can use the Harris-Benedict equation, which takes into account your age, sex, physical activity level, and weight.
Another option is to use one of the online basal metabolic rate calculators that are readily available on the internet. These calculators can give you a rough figure to help you set your energy intake more accurately.
Key takeaways
Your basal metabolic rate is your body's baseline energy expenditure — the energy you need to maintain basic vital functions. For healthy weight loss, it's important to keep a balanced calorie intake that sits between your basal metabolic rate and your total energy expenditure. Eating less than your basal metabolic rate can trigger unwanted responses from your body, including the yo-yo effect.