Metabolism – Converting Food to Energy


Food is fuel and “metabolize” means to change food into energy that can be used by the body.  People don’t have a slow or fast metabolism — it depends on the foods we eat. Some calorie sources rev our metabolism while others cause it to stall.  Namely, carbohydrates speed up our metabolism, while fat and excess protein cause metabolism to slow down because of the extra steps the body has to go through to try to use fat or protein for fuel.  Carbohydrates are the body’s preferred and primary fuel source.  That’s why athletes “carbo-load” before activities.

Metabolism slows down when we eat fattening foods and speeds up when we eat complex carbohydrates.  This is because carbs are the nutrient that the body uses first for energy. It is the body’s preferred energy source.  That is why athletes “carbo-load” before activities, so they have enough energy for endurance.  The body has to go through extra steps to use fat or protein as energy and this takes a toll on organs such as the liver and kidneys.  When you eat too much protein it forces your kidneys to work harder to remove the nitrogen which over time can cause chronic kidney disease and even kidney failure.  When you eat too much fat, it can cause fatty liver disease and type 2 diabetes.

Your calorie intake and your physical activity are what determine what you weigh. Nutrition plays a much larger role than exercise in maintaining a healthy weight and metabolic rate, because you can consume calories much faster than you can burn them.  For example, a study found that the average restaurant meal contains 1,128 calories.  It probably took about a half hour to eat those calories, but it would take over 2 hours of very vigorous exercise to burn those calories.

The more nutrient-dense a calorie is, the longer it takes to burn. Whole plant foods are full of nutrients and fiber, whereas animal products and processed foods are fat- and calorie-dense with few nutrients. That’s why complex carbs are what fuel endurance athletes.  Complex carbs found in beans, legumes, potatoes, whole grains, fruits, and vegetables are much less likely to cause weight gain than fats or simple carbs, like those found in meat, cheese, sodas, cookies, pastries, candy bars, cereals, ice cream,  donuts, etc.

Basal Metabolic Rate

Even when you are at rest, your body needs energy for all of its “hidden” functions, such as breathing, circulating blood, growing and repairing cells, and more.  The number of calories your body uses to carry out these basic functions is known as your basal metabolic rate.  Energy needs for your body’s basic functions stay fairly consistent and aren’t easily changed.  Your basal metabolic rate accounts for about 60-75% of the calories you burn every day.

About a quarter of your body’s metabolism goes toward operating and maintaining your brain! Billions of chemical signals are constantly being carried between neurons– this process is so arduous that even though your brain is not moving (like the muscles in your legs), it uses around 10 times more calories per pound than the rest of you!

The two factors that determine your individual basal metabolic rate are:

Muscle to fat ratio.  Muscle burns more calories than fat, even at rest.

Healthy or unhealthy foods.  The rate at which our bodies burn calories is directly influenced by the quality of the calories we consume.

Metabolic Syndrome

A whopping 34 percent of U.S. adults have Metabolic Syndrome from eating unhealthy foods such as fatty foods, greasy foods, and processed foods.

Metabolic Syndrome is diagnosed by a co-occurrence of at least three out of five of the following medical conditions: Excess belly fat; High blood pressure; Low HDL (“good”) cholesterol;

Elevated blood sugar; High triglycerides (fat in the blood).

Chronic Metabolic Acidosis

Some common symptoms of being overly acidic are: acid reflux, anxiety, arthritis, brain fog, canker sores, chest pain, fatigue, constipation, depression, headaches, irritability, muscle stiffness, restless sleep, stomach aches, sinusitis, just to name a few.

How do our bodies become too acidic?  An unnatural diet is the primary cause.  A diet that is too high in acid-forming foods will cause the body to become too acidic.  What are the acid forming foods?  Dairy, eggs, animals, sugar, flour, soda, coffee, tobacco, alcohol, chemical additives, preservatives, drugs, and synthetic vitamin supplements – are all acid forming.  How to turn it around?  Eat as many organic greens, vegetables, beans, starches, grains and fruits as you can to squeeze out the acid-forming foods.

3 Factors that determine how many calories your body burns each day:

Basal metabolic rate – The energy needs for your body’s basic functions stay fairly consistent and aren’t easily changed.  Your basal metabolic rate accounts for about 60-75% of the calories you burn every day.

Food digestion accounts for about 10% of the calories used each day.  This stays relatively steady and isn’t easily changed.

Physical activity accounts for the remaining percentage of calories your body burns each day – 15% for inactive people and up to 30% for very active people.

Weight gain is simply the result of consuming more calories than you burn. 

Animal-based foods are calorie and fat dense compared to plant-based foods that are generally low in calories and fat and high in nutrients, fiber and complex carbs to fill you up and keep you energized. You can control the speed of your metabolism by eating nutrient dense, whole plant foods vs. fat and calorie-dense animal foods and processed foods. Plant-based foods allow you to eat more because they are much lower in calories than animal foods, so you don’t have to feel deprived to lose weight.


Exercise has very little to do with weight loss.  It takes running a marathon to lose just one pound of fat!  As they say, “you can’t exercise your way out of a bad diet.” But exercise can do the following to improve your health:

  • Increases blood circulation and delivers oxygen to your cells and brain
  • Tones muscles (Muscle burns more calories than fat when you are at rest)
  • Works your heart muscle so it will work more efficiently and lower your resting heart rate
  • Strengthens bone density
  • Improves mood and energy
  • When you’re active you’ll crave healthier foods and beverages
  • Heightens self-esteem and confidence

Positive changes you can make to your diet, exercise and sleeping patterns will help you have more energy.

Top 10 Reasons You May Be Feeling Tired and Sluggish

  1. Living on fast food and junk food that have no nutrients, fiber or complex carbs — the three things you need most when you’re hungry or tired.
  2. You’re eating too much greasy, oily, fatty food
  3. Not eating enough complex carbs (whole vegetables, starches, beans, fruits and grains)
  4. Eating too much at one sitting
  5. Consuming too much sugar and caffeine that exhausts the adrenal system
  6. Skipping meals or not eating every 3 hours
  7. Not getting enough sleep (7-9 hours is optimal depending on the person)
  8. Not drinking enough water
  9. Lack of exercise
  10. You’re on medication(s)


The thyroid gland produces thyroid hormones which are important in the normal regulation of the metabolism of the body.

The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3). Thyroid cells are the only cells in the body which can absorb iodine. These hormones play a significant role in your metabolism and in energy regulation in the body.

Thyroid disease is extremely common. According to the American Association of Clinical Endocrinologists, 27 million Americans have an over- or under-active thyroid gland. There are numerous things that can go wrong with the thyroid gland, but mostly they fall into three categories, according to

Overactivity or Hyperthyroidism – when the body makes too many of the thyroid hormones

Underactivity or Hypothyroidism – when the body makes too little of the thyroid hormones

Growths – this can include benign cysts, nodules, goiter or cancer tumors of the thyroid gland.

Thyroid disease is strongly linked to diabetes. People with diabetes are approximately 3-5 times more likely to develop thyroid disease as compared to the general population.

The thyroid needs the trace mineral iodine to function properly.  The body doesn’t make iodine, so you must get it from dietary sources.

10 Foods to eat that are good sources of iodine:

Organic potatoes with skin Green Beans
Himalayan salt, iodized salt Bananas
Dried seaweed Strawberries
Organic Navy Beans Dried prunes
Organic Corn Cranberries

Foods to avoid that negatively affect the thyroid gland

Dairy Products

Milk and dairy products are loaded with estrogens from pregnant cows. The hormone estrogen can interfere with your body’s ability to use thyroid hormone. People with hypothyroidism should avoid the intake of dairy products including cheeses.

Fatty Foods

Fats can interfere with the thyroid’s ability to produce hormone. Some health care professionals recommend that you cut out all fried foods, butter, nut butters, mayonnaise, oil, margarine, meats, cheese, and fatty fish/seafood to restore normal thyroid function. Fats have also been found to disrupt the body’s ability to absorb thyroid hormone replacement medicines.


Alcohol consumption can wreak havoc on both thyroid hormone levels in the body and the ability of the thyroid to produce hormone. Alcohol appears to have a toxic effect on the thyroid gland and suppresses the ability of the body to use thyroid hormone. Ideally, people with hypothyroidism should cut out alcohol completely or drink in very careful moderation.

Photo credit:

Article by Christine & Sonny Gray

Buy the book:  Malibu Diet: Have a Summer Body All Year

Related posts