Metabolism- what exactly is it??? It's a term we hear used regularly within the fitness industry however many people don't fully understand what it is and how it affects our body? In this blog, I thought I would enlighten you on some of the simple facts about metabolism.
Metabolism is a term that is used to describe all chemical reactions involved in maintaining the living state of the cells and the organism. It is the process by which our bodies convert what we eat into the energy we need to survive and function. Our energy (or calorie) intake, is used by the cells in our body to power all daily functions from breathing to blinking. Some people have a fast metabolism whereby their bodies burn through fuel (calories) quickly like a hot fire. People with a slow metabolism require less energy to keep these processes going as they don't burn through the calories as fast.
For the processes of metabolism to occur, it relies upon the nutrients we eat. The macronutrients (carbohydrates, proteins and fats) we consume are broken down by the body through digestion in order to provide a readily available energy for our cells.
Our bodies get these nutrients from a variety of sources:
- Carbohydrates - Starches and sugars are major and essential sources of energy in humans. Carbohydrates are the primary fuel source for our body cells - did you know the brain uses glucose solely as a fuel source?
- Proteins - The body uses protein to build and repair tissues, make enzymes and hormones and is also a building block for bones, muscles, cartilage and skin. Proteins like eggs, soybeans, meats and vegetables are broken down by enzymes in the stomach and small intestine into amino acids. Many amino acids cannot be made by the body and so MUST be consumed through the diet.
- Fats - Lipids or fats are broken down into fatty acids and glycerol in the small intestine. Fats are used by the body to:
- help to form the cellular structure;
- forms a protective cushion and insulation around vital organs;
- helps absorb fat soluble vitamins,
- provides a reserve storage for energy
- Micronutrients - minerals, vitamins and water are small enough to be absorbed by the body without being broken down. They don't directly contribute to energy production however are important regulators in metabolic pathways. Some of the important minerals include sodium, potassium, calcium, iron, zinc and magnesium.
What I hope you now grasp is how important nutrition is for metabolism. A good quality diet that is nutrient dense and from a wide variety of sources will go a long way to promoting good health. What we must also appreciate however, is that there are quite a few other facets of our lifestyle that may affect our metabolic rate. Most people can increase or decrease the rate at which they burn calories throughout the day, but many don't know how, or that their gender, daily habits, and even health conditions can affect their metabolism. Now that you understand a little more about metabolism, here are some interesting facts:
- Drastically limiting calories will decrease your metabolism- Our bodies are programmed for survival and when you drastically cut your calorie intake, your body goes into 'famine' mode. It preserves energy and slows metabolism so that you will have enough energy to survive!
- Simple carbs can slow metabolism - simple and refined carbohydrates such as white bread and crackers can slow metabolism. They cause a rapid spike in blood sugar post consumption as they usually have a high glycemic index. This means they are very easily and quickly digested by the body causing a rapid increase in blood sugar and then a rapid drop. With spikes in blood sugar, insulin is secreted by the pancreas which allows your cells to absorb sugar from the blood. Insulin also tells the body to store the sugar for later use as fat. Choosing good quality carbohydrates such as wholegrains, legumes, vegetables and fruits are far better sources for your body to use.
- More lean muscle equates to a faster metabolism - More muscle mass in your body translates to more calories burned, even at rest. Muscle is metabolically active which means it requires more energy to function.
- Men normally have higher metabolism - because of testerone and generally having more lean muscle, men tend to have faster metabolisms. So much so that a study showed men lost twice as much weight in the first 2 months of a weight loss regime compared to women on the same regime.
- Menopause can reduce metabolism - When women go through menopause, their estrogen levels drop which can decrease metabolism. It can also cause them to store more 'belly fat.'
- Health conditions can influence metabolism - Thyroid issues such as hypothyroidism can make weight loss harder as the body doesn't produce as much thyroid hormone. Thyroid hormones control how your body uses food for energy and therefore affects your metabolic rate.
- How much and when you eat affects metabolism - If you skip meals, you may be 'sabotaging' your metabolism. As stated above, we know that blood sugar and insulin spikes are no good for us! When your blood sugar levels are fluctuating from fasting to having a large meal, metabolism is affected. A study showed that mice who were given their daily allotment of food in one large meal developed more metabolic problems and gained more abdominal fat than mice fed several times a day, even though the first group of mice ate less food overall than the second.
- Stress can affect metabolism - When you're stressed, the body releases cortisol. Cortisol can increase your appetite and also encourages the body to store more fat which can slow your metabolism.
- Sleep - Not getting enough sleep (< 7 hours per night) has been shown to impact hormones that control blood sugar and appetite.
- Lifestyle habits - having a moderate intake of caffeine as well as drinking plenty of water has been shown to increase metabolism.
Well I hope you now have a better grasp on the importance of metabolism and how the foods you eat and the lifestyle you lead can impact your metabolic rate. Remember if you have any concerns about your own health, please seek advice from a health care professional who can help you overcome any issues. Everybody is unique and individual and I know personally, I have had good success in consulting a naturopath to give me a better understanding of how I can improve my health. :)