The ever-increasing extent of overweight and obesity is highlighted by the World Health Organization, which found that worldwide obesity has nearly tripled since 1975.  In 2016 more than 1,9 billion adults were overweight, of which over 650 million were obese.  Over 39 million children under the age of 5 were overweight or obese in 2020.  The world population in 2021 was close to 7,9 billion.

In the 1960’s and 1970’s the buzz words in food and diet became “low fat”, following on (largely incorrect) assumptions that obesity and related metabolic syndrome disease (characterized by abdominal obesity, high triglycerides, high blood pressure, high blood glucose, and low HDL cholesterol) were caused by food high in fat, including the healthy fats.  Food manufactures reduced the fat content, but to make the processed food still palatable, they added sugar to improve the taste.  Scientists claim this was the start of the worldwide obesity pandemic.

Less intense than cocaine and heroin, but nonetheless addictive for some people, sugar activates the same region in the brain that makes you experience a high and feelings of pleasure.  Like using hard drugs, bingeing on sugar blunts the “pleasure” response over time, making you want the sugar fix more frequently and in higher doses to experience the same feelings of pleasure.

As natural sugar is high in calories and a high intake can lead to weight gain, many people switch to artificial sweeteners, which are made from synthetic chemicals that give a sweet taste without the calories.  As artificial sweeteners are 200 times or more sweeter than sugar, much less is required to sweeten food and soft drinks.  While artificial sweeteners can lower blood sugar levels and may help with weight loss in the short term, research has indicated that a high intake of artificial sweeteners over the longer term may confuse your body into storing fat and inducing diabetes.

This highlights the need for a sugar substitute that is palatable and safe, with no adverse effects on energy metabolism and glucose homeostasis, which refers to a balance in the blood glucose levels.  The pancreas plays a major role in this regard, as it releases more of the hormone insulin when blood sugar levels are high.  When blood sugar levels drop, the pancreas releases more of the hormone glucagon to raise blood sugar levels to maintain balance in blood sugar levels.

One of the promising alternatives to sugar or artificial sweeteners is allulose, a natural sugar present in limited quantities in nature.

What is allulose?

Allulose, the latest in sweeteners, is a naturally occurring sugar with very low calories, only about 10% of the calories of sugar, with the same taste and about 70% of the sweetness of sugar.  As allulose is found in miniscule amounts in nature, for example in kiwis, dried fruit such as figs and raisins, and molasses, it is not cost effective to extract it from these sources, but is commercially produced by converting the starch in corn and wheat with the help of enzymes into allulose.

Types of sugar:

The three major macronutrients are protein, carbohydrates, and fat.  Sugar is a carbohydrate, which is a molecule containing carbon, hydrogen, and oxygen.  Carbohydrates (also known as saccharides) are classified into two groups, namely simple and complex carbohydrates.

  • Simple sugars/carbohydrates: Monosaccharides are made up of a single molecule, such as glucose, fructose, and allulose, while disaccharides are made up of a pairing of glucose and fructose into a two-molecule disaccharide called sucrose.  This is a natural occurrence in nature, for example sugar cane contain high quantities of sucrose, which, when harvested and refined, ends up as table sugar.
  • Complex sugars/carbohydrates:  Oligosaccharides and polysaccharides are complex carbohydrates that are abundant in foods such as vegetables, certain fruits, legumes, and whole grains.

The primary function of carbohydrates is to provide the body with energy, which complex carbohydrates do most efficiently and for longer.  Refined carbohydrates (such as sugar, bread, white rice, pasta) are best used in moderation, or even avoided, as they are high in calories and cause blood glucose spikes.

Sugar (sucrose) consists of glucose and fructose molecules in equal amounts: 

  • Glucose is the primary source of energy for every cell in the human body. The brain, being rich in neurons or nerve cells, is a very energy demanding organ and uses half of all the glucose energy in the body.  About 20% of glucose ends up in the liver, where it is stored as the liver starch, glycogen, which is released as fuel for energy whenever blood glucose levels run low.  The rest of the glucose goes to all the organs and cells in the body.
  • Fructose, on the other hand, is mostly removed from the bloodstream by the liver.  Fructose is metabolized in the liver and turned into lipid (fat) molecules, called triglycerides, with increased uric acid formation.  Excess triglycerides can build up in liver cells, where these “fat spots” can cause liver damage, leading to fatty liver disease, while the rest are released into the bloodstream, and the bulk gets stored in fat cells.

Being very low in calories and with a glycemic index (GI) of zero, allulose has the sweet taste of sugar but without causing blood glucose spikes, promising to be a good alternative for sugar.

Effects of allulose in the body:

Allulose is a carbohydrate, containing carbon, hydrogen, and oxygen, and is classified as a type of sugar with the same chemical formula (C6H12O6) as glucose and fructose.  As a monosaccharide (single molecule of sugar) its physiological impact is quite different from the traditional sugars, as technically no digestion takes place.  It is rapidly absorbed but not metabolized, which means it is nearly calorie-free as none of the calories gets absorbed or stored, and then rapidly excreted.  About 70% is absorbed by the small intestine and then excreted, leaving the body via urine within 24 hours.  The remaining 30% usually passes through the large intestine within 48 hours.  As a result, allulose does not increase blood glucose or insulin levels, says Food Insight, the information hub of the International Food Information Council.

These indications of the effect of allulose on the body results from a few small human studies, each with a limited number of participants.  In essence the studies found that allulose does not affect blood glucose or insulin levels after ingestion.  These pilot observations may well set the basis for large-scale research in this regard. 

Studies also did not investigate whether allulose would have the same “empty calorie” effect on the body that artificial sweeteners have.  Research has indicated that a high intake of artificial sweeteners over the longer term may confuse your body into storing fat and inducing diabetes.  In addition, a high intake of artificial sweeteners has been linked to various adverse health conditions, such as weight gain, metabolic syndrome, Type 2 diabetes, hypertension, and vascular disease.

These health conditions may result from the differences in the way sugar and artificial sweeteners are processed in the body.  When eating something sweet, the brain releases dopamine, which triggers the brain’s reward center.  The reward pathway in the brain consists of a series of connections that deliver neurotransmitters such as dopamine, which makes us feel good.  The first mouthful of sugar activates the taste receptors on the tongue and sends a signal to the cerebral cortex in the brain, which then spikes the release of the neurotransmitter dopamine, which makes you experience feelings of pleasure.  Artificial sweeteners also activate reward pathways, as they provide the pleasure from being sweet, but the pleasure pathway does not get deactivated, since the expected calories do not arrive, which may result in carb cravings.  Experiencing less pleasure in the brain from the consumption of artificial sweeteners can result in overeating other foods with a high calorie count to feel satisfied, compared to eating real sugar.


Natural sweetness that tastes the same as sugar, without the calories, means allulose looks promising to reduce carbohydrate levels in processed and other foods, to address ever increasing overweight and obesity tendencies around the world.

Further studies are, however, needed to explore the underlying mechanisms by which allulose reduces glucose and insulin levels, and its long-term effects on the body.


What is allulose?  Published 10 February 2021.  The Unsweetened Tooth.  (

What is allulose?  Published 15 December 2021.  Food Insight.  (Information hub of the International Food Information Council.  USA.)  (

What is allulose?  Published online.  Allulose Org.  USA.  (

Allulose:  What to know about this sugar alternative.  Published 29 September 2021.  WebMD.  (

Effects of D-allulose on glucose tolerance and insulin response to a standard oral sucrose load:  results of a prospective, randomized, crossover study.  Published in BMJ Open Diabetes Res Care.  2021; 9(1); e001939.  National Center for Biotechnology Information.  U.S. National Library of Medicine.  National Institutes of Health.  USA.   (

Rare sugars and their health effects in humans:  a systematic review and narrative synthesis of the evidence from human trials.  Published in Nutrition Reviews, Volume 60, Issue 2, February 2021, pages 255-270.  Oxford University Press.  Oxford University.

How safe is the newest “natural” sugar substitute?  Published 30 November 2015.  Yahoo!Life.  (

Allulose in human diet:  the knowns and the unknowns.  Published 19 August 2021.  Cambridge University Press.  Cambridge University.  (

Obesity and overweight.  Published 9 June 2021.  World Health Organization.  (


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