Metabolism is actually an umbrella term for all the different chemical reactions in your body that convert food into energy. When you hear it used, it's most likely in reference to your metabolic rate.
The higher your metabolic rate, the more calories you burn and the easier it is to lose weight. Several things can influence this, including genetics, age, body composition, gender, weight, height and diet.
If you're looking to boost your metabolic rate, there are natural ways to do it. But there are also a lot of myths out there surrounding metabolism. We break down some of the big ones.
Breakfast is the most important meal of the day–or is it? Despite this popular saying, research hasn't found any connection between breakfast and faster metabolic rates.
Chances are this myth came about because studies have shown that metabolism does slow down to save energy when the body goes into 'starvation mode'. Basically, if you're on a long-term crash diet and severely restricting what you eat, your body won't be getting enough energy, so it will try to conserve what it's already got (just one reason why crash diets aren't very good for you). Therefore, if you skip breakfast, you would have effectively fasted for 12 – 15 hours before the next meal. If this continues over a period of time, it will affect your metabolism rate.
There's no evidence to suggest that a shorter break (like a night's sleep) will affect your metabolic rate in the same way, or that eating breakfast will boost its speed come morning.
It's likely you've been told at least once in your life that 'eating little and often' is better for your metabolism than eating 3 square meals a day. The truth is, while nibbling throughout the day might stop you from binge eating later, it won't make any difference at all to your metabolic rate.
Here's how it really works. Your body expends energy when digesting food (so you'll be burning calories while you eat). This is known as the 'thermic effect of food' (TEF). The percentage you burn is usually around 20 – 30% of calories for protein, 5 – 10% for carbs and 0 – 3% for fat, or an average total TEF of around 10% of your total calorie intake.
And it doesn't make a difference how many meals you eat. Eating 8 meals of 300 calories will result in the exact same TEF as eating 3 meals of 800 calories each. In both cases, with an average TEF of around 10%, you'd burn around 240 calories while eating that day.
This is supported by numerous studies showing that eating little and often won't result in more calories burned or more weight lost. In fact, sometimes eating smaller meals can actually make you feel hungrier and more inclined to overeat. So, how often you eat really depends on what works best for you. What matters is the distribution of calories you get from protein, fat and carbohydrates. A diet higher in protein is generally beneficial to your health.
OK, metabolism tends to slow down with age, but it doesn't always, and you can definitely do something about it!
Physical activity levels tend to drop as you get older, which can significantly affect the speed of your metabolism. Studies have shown that staying active can make a huge difference in preventing your metabolism from slowing down. In addition, it's common to lose muscle mass as you age (roughly 3 – 8% of muscle during every decade after 30), which can also negatively impact your metabolism. Exercising regularly and consuming plenty of protein-rich foods will go some way towards countering this.
Speak to a doctor if you need advice on exercise, diet or other lifestyle changes to maintain an optimal metabolic rate!