The Low Down on Metabolism

The Low Down on Metabolism

Metabolism. We’ve all heard the word tossed around casually. “I’m overweight because my metabolism is too slow,” or “My metabolism is too fast, I just can’t seem to gain weight” are oft-repeated phrases, so we know that metabolism has something to do with the appearance of our bodies and our weight – but how, exactly? 

    A person’s metabolism is defined as the total of all the chemical reactions that go on in their cells. Furthermore, these chemical reactions can lead to one of two things concerning our weight and appearance – anabolism (building up of body compounds) and catabolism (breaking down of body compounds). The human body is constantly building and breaking things down in order to obtain energy – this means that we are always gaining and losing weight, albeit in tiny amounts at a time. Our energy (measured in calories, another familiar term) is obtained through the food we eat. So do the foods we eat affect our metabolism? 

    You bet. About a thousand calories a day are necessary to adequately maintain vital body functions, and many more calories are necessary in order to perform physical activity. Eating more calories than you expend will always lead to weight gain, no matter what type of macronutrient (protein, carbs, or fats) the calories are coming from. The body is biologically conditioned to store all of these excess calories of energy as fat – the most energy-dense of the macronutrients. Muscle is only built when physical activity is performed routinely. The reason for this is simple – muscle tissue requires a large amount of energy to maintain. Therefore, the body only wants to hold onto as much muscle tissue as it absolutely needs. 

    The point to take from above is simple: Eat too much and neglect to work out, and your body will gain fat. Logic would claim, then, that if you eat too little you would lose weight and/or fat. Is this true? Eat too little and yes, your body will experience a state of catabolism and you will lose weight. This may seem good at first, but let’s delve deeper. Your brain and red blood cells, both vital to life, need a constant supply of glucose to operate. In a body devoid of calories, this glucose is found in pyruvate – an amino acid in proteins. This is where the downward spiral of eating too little begins. Muscle tissue (a primary source of proteins) must be broken down to obtain glucose. This process is inefficient, providing only about a ½ gram of glucose for every gram of protein catabolized. Continue eating too little and the body begins to suppress appetite and slow the metabolism in an effort to conserve body tissues for as long as possible. You are in ‘starvation mode’ – a term I often use to explain the negative effects of fasting to trainees. This slowing of the metabolism leads to a long-term inefficiency when dealing with calorie expenditure, and thus when people consume calorie-heavy “cheat meals”, their bodies store much more of the calories as fat than usual.   

     By now you are probably asking, so how do we win here? Fear not! There are three things that every person can do in order to maintain a healthy weight and metabolism:

  1. Work out! Regular physical activity urges the body to promote muscle anabolism (growth) with those excess calories that we are sure to consume at some point. This is a double-positive. More muscle means that our metabolism becomes ‘faster’, because maintaining muscle tissue burns calories! Also, the physical activity itself causes the body to expend calories so that you are less likely to be in excess of your daily calorie needs. 
  2. Find out your BMR! Your BMR, or basal metabolic rate, is the amount of calories that you expend daily for bodily functions. This number, when taken into consideration alongside the calories expended during a workout, will help you determine your daily calorie goal in order to maintain your current weight. Losing and gaining (healthy) weight is simple once you have this, because you can adjust your caloric intake to support whichever goal you desire! 
  3. Spread out your meals! It’s becoming common knowledge that eating more, smaller meals throughout the day is better than eating few, large meals. Why is this? Eating many small meals assures your body that you are not in danger of a caloric deficiency, and prevents you from entering the dreaded ‘starvation mode’. It prevents the slowing of your metabolism and helps maintain the muscle mass that you’ve worked so hard to gain! 

    Get informed, eat well, and train smart – it’s all about building a better you! Until next time.

- Anna Sherman