Why Can’t I Lose Weight?

Spread the love
fat in gym photo

Photo by ~Twon~

You’ve gone to the gym to do aerobics. You’ve done crunches and tried hours of spinning classes. You’ve done resistance exercises to build muscle to raise your metabolism.

You’ve tried the Zone diet, the South Beach diet, the Mediterranean diet, and even the Weight Watchers diet.

And you’re still ready to shout: Why Can’t I Lose Weight?

Missing Key to Weight Loss

You probably know that to lose weight, especially to lose fat, you need to cut back on calories. Calories represent the energy value of foods. Now, the cells of your body get their energy from these sources:

  • Carbohydrates provide 4 calories per gram
  • Proteins provide 4 calories per gram
  • Fats provide 9 calories per gram
  • Ketones provide 4.5 calories per gram
  • Alcohol provides 7 calories per gram

Obviously, you may be thinking, the best way to cut back on calories is to limit your intake of fat and alcohol since they provide the most calories per gram. This gives you the greatest reduction in calories for the least reduction in the amount of food you worn’t be eating.

But, the real secret to efficient weight loss comes when you know how the body uses the energy from these sources.

The cells of your body primarily use glucose and fat for energy. So, lets concentrate our attention on these energy sources more carefully.


Glucose comes primarily from carbohydrates when they are digested. But, it also comes from glycogen stored in the liver and skeletal muscles and it can be manufactured by the liver (a process called gluconeogenesis).

Carbohydrates come from three basic sources: starch (like potatoes and rice), sugar, and fiber.

Starch and sugar are primarily just chains of sugar molecules. They are broken apart by enzymes during digestion and pass into the blood stream. Fiber cannot be broken down and helps move waste products along your digestive tract.

Table sugar is a simple carbohydrate called sucrose. It consists of a glucose molecule and a fructose molecule joined together. Digestion breaks apart these sucrose molecules via the enzyme sucrase to glucose (blood sugar) and fructose. These smaller molecules then enter the blood stream. Fructose, though it tastes really sweet, cannot be used by the body and most of it is stored in the fat cells.

Excess carbohydrates (that are not stored as glycogen or used for energy) are converted by the liver into fat in a process called de novo lipogenesis.


Fat is digested in the small intestine where the enzyme lipase separates fat globs into fatty acids and monoglycerides which are then converted into triglycerides and enter your lymph system. They can be used to build cell membranes, build myelan sheaths that coat your nerves, insulate your body or be used as fuel when glucose is in low supply. They eventually enter your blood system are are stored in adipose tissue (your fat cells) to build up your fat storage.

When fat in your adipose tissue is ready to be burned as fuel, the triglycerides are broken down into fatty acids and glycerol.

The fatty acids move to cells that need energy and are used as fuel.

The glycerol is used by the liver to make glucose in the process of gluconeogenesis.

What About Ketones?

Ketones do not come from food. Your liver produces ketones from fat.

Your brain uses about 500 calories per day to think and send signals to control all the processes of the body.

When glucose is plentiful, your brain uses glucose for energy. But, your brain cannot use fat for energy.

Instead, when glucose is in short supply, your brain uses ketones.

So, the level of ketones in your body is an indicator of what your body is burning as fuel.

You sometimes will want to measure the ketones in your body with urine test strips or a ketone breath monitor to ensure you are primarily burning fat rather than glucose.

What Determines if You Burn Fat or Glucose?

One main regulator is insulin. It works to help protect your body from high glucose levels.

When you consume a heavy carbohydrate meal, lots of glucose floods the bloodstream.

If you are unable to lower the concentration of glucose in your bloodstream you may experience negative symptoms of high blood sugar (hyperglycemia) such as

  • Increased thirst or hunger
  • Frequent urination
  • Sugar in your urine
  • Headache
  • Blurred vision

Long term effects of frequent hyperglycemia include:

  • Damage to your eyes, blood vessels, nerves, kidneys other organs
  • Cardiovascular problems
  • Stroke
  • Problems healing wounds

So, insulin works to lower glucose levels in the blood. It stops your fat cells from releasing stored fat and ensures that your body’s cells use glucose for energy.

Excess glucose is sent to the liver to produce more fat (lipogenesis) for storage.

Another regulator of the energy process is the hormone glucagon.

When glucose and insulin levels are low glucagon causes fat to be released from the fat cells so the fatty acids can be used for energy.

You Want to be a Fat Burner

To control your weight, especially your fat, you need your body to be a fat burning machine.

Your goal should be to reduce the amount of insulin so fat can be released from your fat cells and used for energy.

The way to do this is simple: restrict your carbohydrate intake. This means limiting your intake of foods like:

  • Sugars
  • Bread and all grains (wheat, barley, rye, oats, rice, and cornmeal)
  • Beans and all legumes
  • Potatoes
  • Cookies and other desserts
  • Pasta
  • Corn (and sweeteners made with corn)
  • Fruits

Sounds pretty restrictive, doesn’t it? Well, people who love carbs remain sugar burners and let high insulin levels lock their fat in their fat cells.

What’s the Evidence?

A two year study reported in The New England Journal of Medicine compared that effects of a low carbohydrate diet, the Mediterranean diet, and a low fat diet. The study began with 322 moderately obese subjects in a workplace with an on-site medical clinic.

The low fat diet was based on the American Heart Association’s guidelines. Calories were restricted to 1500 for women and 1800 for men with 30% of the calories from fat.

The low carb diet was based on the Atkins diet. It started by restricting carbohydrates to 20g per day for the first two months, then gradually increasing carbs to 120g per day to maintain the weight loss.

The Mediterranean diet was based on the recommendations of Willett and Skerrett. Calories were restricted to 1500 for women and 1800 for men. The diet was high in vegetables and low in red meat.

What were the results?

All three groups lost weight. The weight loss for the low carbohydrate diet was most dramatic. Only after several months when more carbs were added to the diet did the weight loss start to level out and then weight increased somewhat.

As you can see from the above weight loss graph, reducing carbs makes the dramatic difference. The conclusion is simple: If you want to lose weight, restrict your carbs.

Another study reported in The American Journal of Clinical Nutrition involved 17 obese men in a residential clinic with a BMI greater than 30. The study wanted to compare the results of a high protein low carbohydrate diet to a high protein moderate carbohydrate diet. Neither diet restricted calories.

This was a crossover study, in that all participants tried both diets. All subjects started with a 3 day maintenance diet. Then for 4 weeks half the subjects ate a high protein, low carbohydrate diet and the other half at the high protein, moderate carbohydrate diet. Then there was another 4 days of a maintenance diet. After that the groups switched diets. Then the subject had another 3 day maintenance diet.

The results demonstrated the value of the low carbohydrate diet (ketogenic) for weight loss. First, the subjects reported being less hungry on the low carbohydrate diet. And, second, the subjects lost more weight, including fat, on the low carbohydrate diet as shown in the following graph:

Theory and Evidence Support a Ketogenic Diet

The message is clear. To lose weight, especially fat, cut your carbs.

Cutting carbs is the key to fat loss. The proof is clear. The evidence is overwhelming.

Benefits of the Ketogenic Diet

Dr. Josh Axe shares with you the benefits of a ketogenic diet. Ketogenic diets can actually help weight loss, cancer, and even Alzheimer’s disease. When you are on a ketogenic diet, you are putting your body into a state of ketosis, which means your body is burning fat for energy rather than carbohydrates. The ketogenic diet could be the best diet for fat loss, however I don’t believe anyone should be on this diet for more than 3-6 months. The reason why this diet works so effectively is your body stops feeding on sugar and starts burning fat. The diet consists of about 80% fats, 10% carbohydrates, and 10% protein.


Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet published in The New England Journal of Medicine

Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum published in The American Journal of Clinical Nutrition

2 thoughts on “Why Can’t I Lose Weight?

Leave a Reply