Does eating fat affect blood sugar levels?

(Last Updated On: September 22, 2017)

Fat only affect blood sugar levels if carbohydrates are consumed with it



onsuming fat alone does not raise blood sugar levels, but carbohydrates eaten along with fat will. Consumption of saturated or unsaturated fats do not raise your blood sugar because calories from fat are not converted into glucose immediately. They are converted into energy by a process called gluconeogenesis which takes place in the liver[1,3,6]. Your liver convert fat into glucose when you are not eating, in order to maintain glucose safe levels.

The body then uses mainly two methods of producing energy:

  1. ATP from glucose: The easiest way for the body to make glucose is from carbohydrates. Most people today are constantly eating carbohydrates and therefore processing glucose from carbs. They are carb burners
  2. ATP from fat: We can quickly alternate between fat and glucose burning mode several times a day; at least we should.  You body can just as well make energy from fat. There are a lot of advantages being a fat burner rather than a carbohydrate burner.

If you are mostly a fat burner you have more endurance for physical activity; your energy levels will be more even all day. Another great advantage is that you actually “burn fat” rather then store it. You can skip a meal and still be functioning just fine because your body knows how to tap into fat reserves for energy. Having a diet rich in fats and proteins is the best way to insure you have enough ATP but only use it when needed; thus creating a more efficient process. This is the best way to avoid hyperglycemia because it helps to reduce excess blood glucose circulation. Being a fat burner is like having a “energy on demand” system in place.

The first choice for energy production is glucose because it is ready to be used. It is the easiest an quickest energy form your body can access. If your body is not creating energy from carbohydrates it can make it from: 1) gluconeogenesis which is energy from fat and 2) glycogen which is stored ready to use glucose. However there is a complex and intricate system selecting what source of energy the body will use; either after you eat or between meals[1,2,3,4].

How our bodies can became fat burner or carb burner depends largely on our lifestyle which ultimately affect our metabolism. Obesity, diabetes and other metabolic conditions all play a fundamental role on how this system works. Changes in muscle mass, diet and energy expenditure will dramatically change the way our body produces energy. Remember that we eat to produce energy, a concept we easily forget because food is also for pleasure and part of social life.

The two pathways for ATP creation can be activated or not. This depends on how much fat, carbs we eat, and how much we exercise. It also depends on how much muscle mass we have. If you eat to much carbohydrates all the time you’ll inhibit your ability to burn fat. One the other hand if your eat more fat and your have more muscle mass you’ll stimulate your “fat burning” pathway and set it up as your default mode. If your diet is mostly carbohydrates the body automatically switch the system to “carb burner” and just keep it there.


Being a fat or carb burner and the metabolic inflexibility 

There are two main pathways used to create energy or ATP: one is from fat the other is from sugar (carbohydrates). The body should be able to freely switch between both as its primary energy fuel source. If burning fat is our most efficient way of making energy, why are not burning more fat on regular basis? Our ancestral family used to be more of the fat burners type. Our diet today consist of mostly carbohydrates which create hyperinsulinemia a condition characterized by a sharp insulin production on a short period of time.

New studies are showing us that insulin resistance and diabetes type 2 have a strong link to our inability in processing energy from fat when we are not eating. There is also a strong correlation between being a mostly carbohydrate burner and the inability to switch between these two main modes of energy production. When we are in glucose mode all the time, our fat burner mode can’t work properly. This called “metabolic inflexibility”. This inflexibility can also impair the ability to process fat when fat is available or after fat is consumed. In other words we became fatter after we eat when we could be burning that same fat for energy.

New studies are showing new data demonstrating that fat consumption can trigger the “fat burning” mode. Of course the hallmark of diabetes is obesity and excess fat which can cause insulin resistance; so there is a catch 22 effect here. How do we reduce fat by eating more fat? In order to achieve that we have to switch on our fat burning system first. The fastest way to achieve this is with exercise and most specifically building muscle and eating less carbohydrate.

Have in mind that we eat in order to have energy and that is intimately linked to our muscles needs. If we create a need for energy and provide our body the right nutrition; the body will activate the fat burning system because it is a more efficient energy system. Better yet it will be able to switch between glucose and fat burning as needed. You’ll be able to eat more carbohydrates and still have a better glycemic control whether you are diabetic or not. A diet rich in fats and low in carbohydrates is ideal.

The importance of muscle to become a “fat burner” type

Muscle mass is the most important player in the activation of the fat burning mode. At rest, about 60-80% of energy provided to muscles come from fat burning and not carbohydrate. Muscles are also the largest consumers of oxygen due to its large mass. During exercise the oxygen consumption increases dramatically to 350 mL O2/Kg. Muscles are also responsible for the uptake of glucose when glucose is abundant and it prevents hyperglycemia. When insulin is present after stimulation from a glucose rich foods, 80% of glucose uptake is accounted for by your muscles.

Hi fats diet for diabetes

A high fat – low carbohydrate diet can lower weight and lower A1c levels [1]. Lowering the consumption of carbohydrates alone will lower your A1c levels. In a study published Published: 8 April 2008 in
Nutrition & Metabolism 14 days of low carbohydrate diet decreased plasma glucose levels and hemoglobin A1c from 7.3% to 6.8%. You don’t have to use large amount of fat to replace carbohydrates [1,2,5,7,8].

Eating more fat and protein puts your liver in charge of accessing and processing how much glucose is needed and glucose production is evenly regulated. Glucose from carbohydrates is converted immediately and whatever is not used is stored as fat. A diet rich in fats is good for diabetics because it prevent fat storage and increase insulin sensitivity.

A diet rich in proteins and fat could be a good alternative for diabetics however some changes need to be made before you adopt it. Not all fats are created equal we first need to understand the different qualities between fats. This is perhaps the most controversial diet today. Saturated fats have been demonized and banished from our diet but recent studies have uncovered controversies. Earlier studies which have failed to provide hard evidence proving links between saturated fats and heart disease; the same goes for cholesterol.

First you must lose weight and get your fat burning system started. You need to start cutting carbohydrates and substituting it with fats and proteins. Most importantly you need to start strength exercises so your energy expenditure are are high and you are able to process the rich nutrients contents of fat.

Today there still no conclusive hard evidence which proves saturated fat is the cause of heart disease. Talking openly about fat is not easy because we have solidified the idea that fat is indeed bad. Valid information in this matter is hard to find and most articles are heavily biased in favor of a fat free, high carbohydrate diet even though high carbs might be causing us more harm than good.

Even though fat does not raise blood sugar most sources of information will say it does. Fats slow glucose absorption. It is not fat which raises blood glucose but the carbohydrates you consumed with fat; which show up 2 hours later.

There are many factors involved with our nutrition which are important. The quality of foods we eat, how much we exercise and the level of activity we do; the combination of foods we eat; the kind of fats and the kinds of carbohydrates we eat. Having a high fat diet doesn’t mean we can just indulge into everything that has fat in it. There are many types of fats like saturated fats and unsaturated oils. Stay with the most wholesome and natural foods as possible. You should not eat fried foods for fat or after being heated to high temperatures; this changes fat’s chemical structures and it might harmful for your health [1,2,5,7,8].




  1. Metabolic flexibility in the development of insulin resistance and type 2 diabetes: effects of lifestyle.
  2. In type 2 diabetes, randomisation to advice to follow a low-carbohydrate diet transiently improves
  3. Dietary carbohydrate restriction in type 2 diabetes mellitus and  metabolic syndrome: time for a critical appraisal
  4. Metabolic interactions between glucose and fatty acids in humans
  5. Blood glucose patterns and appetite in time-blinded humans: carbohydrate versus fat
  6. Saturated fat, carbohydrate, and cardiovascular disease
  7. Carbohydrate Restriction has a More Favorable Impact on the Metabolic Syndrome than a Low Fat Diet
  8. An increase in dietary protein improves the blood glucose response in persons with type 2 diabetes
  9. Dietary fats and prevention of type 2 diabetes
  10. The effect of a low-carbohydrate, ketogenic diet versus a  low-glycemic index diet on glycemic control in type 2 diabetes mellitus
  11. Extended effects of evening meal carbohydrate-to-fat ratio on fasting and postprandial substrate metabolism
  12. Saturated fat, carbohydrate, and cardiovascular disease
  13. The Soft Science of Dietary Fat
  14. Essential fatty acids in health and chronic disease
  15. Effects on Coronary Heart Disease of Increasing Polyunsaturated Fat in Place of Saturated Fat: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
  16. A Reduced Ratio of Dietary Carbohydrate to Protein Improves Body Composition and Blood Lipid Profiles during Weight Loss in Adult Women

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In Category: DIABETES

Marcos Taquechel

Marcos is an RN. Thanks for stopping by and reading my posts. I hope you are able to get something useful out of this blog. Take good care of yourself and don't worry about anything until you have something to worry about.

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