Well Mama Weblog

Is our metabolism to blame?

by Viviane Höger

Do you know anyone who complains about having a slow metabolism and how they barely eat anything yet still gain weight? Or perhaps you know someone who appears to be able to eat whatever he or she likes — including large portions of junk food, and they never gain weight. These scenarios raise very good questions about our metabolism:

  • What role exactly does metabolism play in weight gain or weight loss?
  • Is your metabolic rate determined by your genes? If so, can you speed up a slow metabolism through exercise, drugs or certain foods?
  • Is the importance of metabolism just a myth? Is weight gain or loss purely due to "calories in and calories out?"

The answer to these questions involves a mix of nature (genetic make-up) and nurture (the environment).

It's part truth and part myth that metabolism is the key to our weight. The rising tide of obesity we see in developed countries cannot be blamed entirely on an inherited tendency to have a slow metabolism. Genes do not change so quickly.  The fact is, contrary to popular belief, a slow metabolism is rarely the cause of excess weight gain. 

Although our metabolism influences our body's basic energy needs, how much as well as the quality of we eat and drink along with how much physical activity we get are the things that ultimately determine our weight.

What is metabolism?

Metabolism is the process by which your body converts what you eat and drink into energy. During this complex biochemical process, calories in food and beverages are combined with oxygen to release the energy your body needs to function.

Even when you're at rest, your body needs energy for all its "hidden" functions, such as breathing, circulating blood, adjusting hormone levels, and growing and repairing cells. The number of calories your body uses to carry out these basic functions is known as your basal metabolic rate — what you might call metabolism. The average basal metabolic rate for women is around 1450 calories.

One way to think about metabolism is to view your body as a car engine that is always running. When you're sitting still or sleeping, your engine is ‘resting’ like a car at a stop light. A certain amount of energy is being burned just to keep the engine running. Of course, for humans, the fuel source is not gasoline. It's the calories found in foods we eat and beverages we drink — energy that may be used right away or stored (especially in the form of fat) for later use.  

How fast your body's "engine" runs on average, over time, determines how many calories you burn. If your metabolism is "high" (or fast), you will burn more calories at rest and during activity. A high metabolism means you'll need to take in more calories to maintain your weight. That's one reason why some people can eat more than others without gaining weight. A person with a "low" (or slow) metabolism will burn fewer calories at rest and during activity and therefore has to eat less to avoid becoming overweight.

Several factors determine your individual basal metabolism, including:

  • Your body size and composition.  People who are larger or have more muscle burn more calories, even at rest.
  • Your sex.  Men usually have less body fat and more muscle than do women of the same age and weight, which means men burn more calories.
  • Your age.  As you get older, the amount of muscle tends to decrease and fat accounts for more of your weight, slowing down calorie burning.

Energy needs for your body's basic functions stay fairly consistent and aren't easily changed.

In addition to your basal metabolic rate, two other factors determine how many calories your body burns each day:

  • Food processing (thermogenesis). Digesting, absorbing, transporting and storing the food you consume also takes calories. About 10 percent of the calories from the carbohydrates and protein you eat are used during the digestion and absorption of the food and nutrients.
  • Physical activity. Physical activity and exercise — such as working out at the gym, walking to the shops, chasing after the dog and any other movement — account for the rest of the calories your body burns up each day. Physical activity is by far the most variable of the factors that determine how many calories we burn each day.

Scientists call the activity you do all day that isn't deliberate exercise non-exercise activity thermogenesis (NEAT). This activity includes walking from room to room, gardening and even fidgeting. NEAT accounts for about 100 to 800 calories used daily.

Metabolism and weight

It may be tempting to blame your metabolism for weight gain. But because metabolism is a natural process, your body has many mechanisms that regulate it to meet your individual needs. Only in rare cases excessive weight gain results from a medical problem that slows metabolism, such as Cushing's syndrome or having an underactive thyroid gland (hypothyroidism).

Unfortunately, weight gain is a complicated process. It's likely a combination of genetic makeup, hormonal controls, diet composition and the impact of environment on your lifestyle, including sleep, physical activity and stress.

Regardless of whether your metabolism is fast or slow, our bodies are designed to store excess energy in fat cells. So, if you eat and drink more calories (energy "intake") than your body expends (energy "output") you will gain weight. On the other hand, if you eat and drink fewer calories than are burned through everyday activities (including exercise, rest and sleep), you'll lose weight. Our bodies are also programmed to sense a lack of food as starvation. In response, our BMR slows down, which means fewer calories burned over time. That's one reason why losing weight and keeping it off is often difficult.

Evidence seems to suggest that, generally speaking, the metabolism slows down as we get older, which may be why some people suddenly find it harder to keep extra weight off (but of course, this isn’t the case for everyone). 

The most significant change that takes place in our bodies as we get older is the loss of lean muscle tissue, which is mostly replaced with fat. This process, known as ‘sarcopenia’, will occur naturally- unless you continue to follow a muscle-building regime and obtain sufficient protein in your diet to build new muscle.

Resting metabolism is thought to slow down by around 5% every 10 years after age 25 and as a result, our daily need for calories goes down. By the time a woman is 75, she actually needs around 300 calories less per day than when she was 18, and 130 calories less per day than when she was 50. The difference is even greater in men, who need around 655 fewer calories per day at age 75 than when they were 18 years old.

Metabolism and physical activity

Lean people tend to be more active during everyday activities than people who are overweight. How? They may "fidget" more — that is, they tend to be in motion even when engaged in non-exercise activities. Whether this tendency to move more or less is genetically programmed or learned remains uncertain. But it can add or subtract hundreds of calories each day.

Overweight people expend more calories, on average, than lean people during most activities, in part because it takes more effort to move around. But they tend to be more sedentary, which makes it harder to get rid of body fat.

What can I do to burn more calories and help my metabolism along?

  • Regular aerobic exercise.Aerobic exercise is the most efficient way to burn calories and includes activities such as walking, bicycling and swimming. As a general goal, include at least 30 minutes of physical activity in your daily routine.  If you want to lose weight or meet specific fitness goals, you may need to increase the time you spend on physical activity even more. If you can't set aside time for a longer workout, try 10-minute chunks of activity throughout the day. Remember, the more active you are, the greater the benefits.
  • Strength training: strength training exercises, such as weightlifting, at least twice a week. Strength training is important because it helps counteract muscle loss associated with aging. And since muscle tissue burns more calories than fat tissue does, muscle mass is a key factor in weight loss.
  • Lifestyle activities.Any extra movement helps burn calories. Look for ways to walk and move around a few minutes more each day than the day before.  Taking the stairs more often and parking farther away at the store are simple ways to burn more calories. Even activities such as gardening, washing your car and housework burn calories and contribute to weight loss.

Can you re-set your metabolism by changing your dietary habits?

Yes. Our metabolic rate is not set, we know for example that we can speed it up with physical activity. But can we do the same by changing our eating habits? Most definitely yes. Influencing your body to break down food and transform it into energy more efficiently is possible, and most of us could benefit from it. 

Eating enough protein, drinking enough water, and leaving breaks between meals are some of the scientifically backed methods to speed up your metabolism, and a part of the core rules that make up the Metabolic Balance® nutrition program.

What is Metabolic Balance®?

Metabolic Balance® is a three-month programme designed to re-set your metabolism and hormone levels, particularly insulin, in order to enable your body to reach its natural weight. The programme is based on creating stable insulin levels through a healthy diet so that you will feel satisfied after meals and balance your body’s metabolism.  It is based on two major concepts:

  1. Everybody has the capacity to produce all the hormones and enzymes necessary for a healthy metabolism. However, to support this process we need to supply the body with adequate nutrients, which are obtained from REAL food.
  2. Our body has the ability to develop an appetite for foods containing the nutrients it needs. However, instead of listening to internal messages most people select foods based on external stimuli.

The programme starts with a comprehensive blood test.  The results of this blood test then determine your unique nutrition plan.  The long-term goal of the programme is to create healthy habits through sensible eating patterns. It is totally focused on clean nutrient rich wholefoods, so no diet foods, shakes, supplements or fad ingredients.

At a primary level, scientific evidence suggests that the programme delivers on several health markers, and that it:

  • Increases fat burning;
  • Reduces hunger and cravings;
  • Reduces inflammation;
  • Improves blood cholesterol;
  • Improves glucose levels.

No magic bullet

Don't look to dietary supplements for help in burning calories or weight loss. Products that claim to speed up your metabolism are often more hype than help, and some may cause undesirable or even dangerous side effects.

Dietary supplement manufacturers aren't required by regulating organization to prove that their products are safe or effective, so view these products with caution and skepticism. Always let your doctors know about any supplements you take.

There's no easy way to lose weight. The foundation for weight loss continues to be based on physical activity and often an overhaul of eating habits.  

Want to know more?

For information about the program:

Metabolic Balance® Q&A:

My personal diary and observations:

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