What Affects Metabolism?
Metabolism can be defined as a series of chemical reactions in the cells of our bodies which occur to synthesize energy from the food we consume.
This energy is then used by different body functions that sustain life, from breathing, digestion, movement, growing, even thinking.
In fact, metabolism consists of thousands of chemical reactions occurring simultaneously but regulated by our bodies to keep our cells functioning and healthy. Metabolism occurs through two interactive processes: catabolism and anabolism.
Catabolism is when the composition of food (carbohydrates, proteins, fats) is broken down into simple forms. These simple substances are then used by body cells to create the energy they need.
All anabolic processes in the body, such as heat production and powering muscle contraction and movement, derive energy from these simple substances. Consequently, catabolic reactions release waste products (toxins) which are eliminated from the body by the kidney and liver.
On the other hand, anabolism is the process in which new cells are made. Think of it as your ‘constructive metabolism’. Anabolic processes facilitate cell growth, tissue maintenance and energy storage. Very frequently, people are not aware of the metabolism types and result in misunderstanding of using metabolism to their advantage in weight control.
Factors affecting metabolism
Interestingly, the two metabolic processes work to compliment each other. There are several things that affect these processes. Hormones, the nervous system, genes, gender, external factors, all affect metabolism. However, it’s important to understand the components through which metabolism is affected.
Basal metabolic rate (BMR): refers to the number of kilojoules burned when the body is at rest. It makes up 50 to 80 percent of energy used. This is the energy the body uses to maintain itself, mainly influenced by your lean muscle mass.
If muscle tissue reduces, basal metabolic rate will decrease, hence, preserving muscle is important for weight loss. On average, basal metabolic rate is higher in men than in women (7100kj to 5900kj per day for male and female respectively).
Energy expended during physical activity: this is the amount of energy the body uses while physically active, like moving. Total energy expended at rest is up to 20 percent but increases with physical activity. You only have some control over the energy used during strenuous exercise, thus you can take advantage of this for weight loss purposes. Metabolic rate increases in the hours after physical activity, up to over 5 hours in some cases.
The thermic effect of food: this is the energy expended during digestion of food (from eating to the process of synthesizing energy). In fact, eating food increases your metabolism. This is why going on a diet decreases metabolism, which results in the body burning less calories and reserving fat for energy.
Metabolic rate rises after a meal, hitting a peak 2 to 3 hours later. Depending on meal size and food, the rise can be between 3 to 25 percent, for instance, fatty foods cause the basal metabolic rate to increase by 4 percent, carbs by 6 percent and protein by over 25 percent. Spicy foods cause a high thermic effect.
Age and lifestyle also have an effect on metabolic rate, albeit a very small one. For instance, after the age of 30, there’s a 1 to 2 percent decrease in basal metabolic rate for every decade, while in children, metabolic rate is high due to growth hormone. Slowed metabolic rate in aging persons can be countered through strength training.