How Much Sugar Is Too Much?


How bad is sugar really, and how much sugar is too much? In this article we are going to explore what sugar is, how it affects the body, and whether you should avoid or embrace it as part of your diet. We will also answer the question “how much sugar is too much?” as best we can.

What Is Sugar?

Considering how big a topic sugar is in nutrition, there are a lot of people who could not tell you what exactly sugar is. Sugar is a generic term for any sweet-tasting carbohydrate that can be dissolved in water (soluble).

Simple sugars are known as monosaccharides, there are three: fructose, galactose, and glucose.

Compound sugars are mixes of two simple sugars, their scientific name is disaccharides. The three compound sugars are: lactose, maltose, and sucrose.

Let’s take a slightly more in-depth look at the three simple sugars fructose, galactose, and glucose.

  • Fructose: This is a monosaccharide that is found in fruits and some vegetables (root vegetables such as carrots, sweet potatoes, and corn). Fructose is also found in sugar cane and sugar beet, which is where granulated white sugar comes from.
  • Galactose: When combined with glucose, galactose makes up the disaccharide lactose found in milk. Lactose is broken down by the enzyme lactase, some adults do not produce this enzyme, making them unable to digest dairy (lactose intolerant).
  • Glucose: Also known as dextrose, glucose is found in fruit and vegetables. However, almost all carbohydrates are converted into glucose during digestion. Glucose is transported via the bloodstream and regulated by insulin and glucagon (hormones created in the pancreas) [1].

What you need to understand is that carbohydrates are all broken down into glucose, whether they are starches or sugars. Glucose is the body’s preferred source of energy as it is almost instantaneously converted into energy. That’s why athletes drink high-glucose drinks during training.

Now that you know the three monosaccharides, let’s take a closer look at the most famous of the disaccharides – sucrose.

  • Sucrose: This disaccharide is made up from a combination of fructose and glucose (50% of each), it is found in certain fruit and vegetables. Sucrose is the scientific term for table sugar, and it is the most commonly used sugar in food production. Unlike glucose, sucrose is not as easily used for energy. This is because it is a disaccharide which means that it needs to be broken down first by an enzyme called sucrase.

When people talk about sugar they are often talking about sucrose, even though sucrose can be found in nature, it is often seen as unnatural, mainly because table sugar is processed. Molasses is made from refining sugar cane or sugar beet and actually contains a number of B vitamins as well as some minerals. But when molasses is further refined into table sugar it loses all of these nutrients.

Incidentally, brown sugar does contain these vitamins and minerals, however the amount is so small that they convey no benefits – making white and brown sugar essentially the same from a nutritional standpoint.

Naturally Occurring Vs Added Sugar

A 2009 study compared the effects of a fructose-sweetened beverage and a glucose-sweetened beverage on body fat increases [2]. The study found that fructose-sweetened beverages led to significantly more body fat accumulation than glucose-sweetened beverages. This has led people to claim that fructose is the worst form of sugar.

But let’s take a look at a common source of fructose … fruit. Grapes, pears, figs, apples, bananas, pineapples are all sources of fructose. Pears have the highest ratio of fructose to glucose while figs contain the most fructose per serving.

Many people would say that you should therefore avoid fruit! This is clearly crazy. Fruit is an amazing source of many nutrients and no diet should advise leaving it out. It is here that the whole debate around sugar starts to get complicated.

You see, there is a difference between naturally occurring sugars and sugars that are added to food. Not a chemical difference, both types of sugar are identical and will provide the same number of calories per gram (four). The difference is in the context.

A banana may contain 12.2g of sugar per serving, but it is still low in calories (89 calories per 100g) and high in nutrients (vitamin C, manganese, vitamin B6) and fiber (2.6g per 100g). Whereas a 100g cookie would contain 15g of sugar and be high in calories (500 calories per 100g), and low in nutrients. The actual amount of sugar is similar, but the banana is undeniably healthier.

This doesn’t mean that you shouldn’t pay attention to the amount of sugar present in foods, eating 20 bananas per day will lead to a lot of unnecessary calories being consumed. But you should view the foods you eat in terms of how high in calories they are, how healthy they are, and whether they will improve your diet or not – rather than just focusing on how much sugar they contain.

Sugar And Obesity

In this article we have taken a look at what sugar is, it is a carbohydrate. It contains 4 calories per gram. This is the same as protein (4 calories per gram) and less than fat (9 calories per gram). That means that if you ate 100g of sugar it would contain 400 calories, but if you ate 100g of fat it would contain 900 calories.

Weight gain and weight loss is actually a fairly simple process, it is based on simple mathematics. If the number of calories you consume (calories in) is more than the number of calories you expend (calories out) you will gain weight. If the number of calories you consume is less than the number of calories you expend then you will lose weight.

Weight management is just a question of getting your calories in/calories out balanced to suit your needs. If you want to lose weight, then your diet needs to have a calorie deficit. If you want to gain weight, then your diet needs to have a calorie surplus. If you want to maintain weight, then your diet will need to be completely balanced with your energy expenditure.

But some people, led by famous author Gary Taubes, have come to the conclusion that sugar is the leading cause of obesity. There are a lot of long-running arguments surrounding this debate, with most nutrition and exercise scientists on one side, and Gary Taubes and his adherents on the other.

But can this be the case?

If sugar is the biggest cause of obesity, then surely eating less sugar would lead to less cases of obesity? That would be logical.

But over the last 30 years or so, this has not been the case. If you take a look at this graph produced by Stephen J Guyenet you can see that since the late 90s, sugar consumption has decreased from 110g per day to 95g per day [3].

But obesity levels have continued to rise. There are several reasons why this could be the case, but the most obvious is that something else is the main driver behind obesity.

In 2017, a paper was published in Nutrients Journal, it was a review of dietary macronutrient (protein, fat, carbohydrates) intakes in people living in rural China [4]. It examined how diet had changed from 1991 to 2011.

The study had some very interesting results. Rural people in China were consuming less calories, eating significantly less carbohydrates (and therefore sugar) and yet obesity levels were rising. How could this be?

The researchers theorized that the reason for this was that rural Chinese people were exercising less. Interestingly, the study also found that dietary fat intake had massively increased. Now, we’re not saying that this has led to the increase in obesity (remember overall calorie intake decreased), but if you were looking for something to blame, refined sugar would have to be even less likely than fat.

Now, rural China does not represent the entire planet. There will be places where calorie intake is increasing, and there will be places where obesity levels are dropping. But in the main, people are getting larger. But sugar consumption does not appear to be the issue.

Increased availability of food, particularly high-fat foods (meat and dairy being good examples) combined with less activity (and therefore less calories burned per day) seem to be the most likely contributors.

We’re not saying that sugar is innocent in all of this, a diet that is high in sugar is likely to be a diet that is high in calories. Particularly if your sugar is coming from the things you drink (which would be high in calories but unlikely to keep you feeling full afterwards).

But if you are looking to lose weight (or are looking to give out advice to people who want to lose weight) then you should be concentrating on other avenues. Reducing portion sizes, increasing protein and fiber. Improving sleep quality (which can lead to less calories consumed the next day), increasing exercise and activity levels etc.

Blaming sugar for obesity is short-sighted, obesity is caused by many factors. Sadly, it is not as simple as pointing to a certain ingredient and saying “that’s the one that made me fat”.

Is Sugar Unhealthy?

Another common complaint about sugar is that it is unhealthy, people will say that avoiding sugar will improve your health. This is sort of true in one sense. If you cut down on your sugar intake you might see a reduction in the number of calories you consumed per day (provided you don’t replace those calories with something else). This could lead to weight loss, which has many health benefits.

But sugar itself is not healthy nor is it unhealthy. It can be found in healthy foods such as fruit and vegetables, and it can be found in unhealthy foods such as cakes, chocolate bars, sodas etc.

If you completely cut out all foods that contained sugar (including fruit and vegetables) you would be in danger of suffering from certain nutritional deficiencies. Vitamin A, Vitamin C, B Vitamins, calcium, magnesium, iron etc. are all found in fruit and vegetables, and you would definitely notice changes in your appearance and health if you became deficient in them.

But as this article by Myolean Fitness points out [5] there are several populations that follow a high-sugar diet that are very healthy compared to Western populations. The Kuna Indians of Panama are an example of a population that consumes a relatively high sugar diet, but are perfectly healthy, with lower cases of hypertension than Westerners [6].

If sugar caused ill-health, then societies that consumed high levels of sugar would automatically see higher cases of disease and illness. This does not appear to be the case.

Consuming sugar through fruit, vegetables, grains, dairy, and the occasional treat is perfectly healthy. Avoiding sugar completely is unhealthy. Over-consuming sugar is also completely unhealthy, but mostly due to weight gain from over-consuming high-calorie foods.


So, how much sugar is too much? This is a difficult question to answer. For starters, you’re probably sick of hearing it but EVERYONE is different. A 6-foot 2-inch athlete is going to be able to consume a lot more sugar than a 5-foot, sedentary octogenarian with a bad hip. They both would benefit from individual advice.

It’s also difficult to answer because there isn’t really a right answer. You could, for example say that ensuring that sugar makes up less than 10% of your diet is a good rule of thumb … but it would be possible to live a healthy life with a diet that consists of 20% sugar. Provided that the sugar was coming from fruit and vegetables, and provided that your overall calorie intake was within your needs.

In terms of health, sugar has been proven to be non-toxic in ridiculously high amounts. So don’t worry about it poisoning you!

Let’s try to create some general rules of thumb that everyone can follow:

  • Always prioritize naturally occurring sugars over sugars that have been added to foods (I.e. apples over apple pies)
  • Concentrate on your calorie intake vs your calorie expenditure. Make sure that you are not creating a surplus which will lead to weight gain and obesity
  • Stay active and look to fuel your more intense sessions with glucose drinks, the simple sugar will help improve your training session. This is using sugar for a positive reason.
  • Concentrate on other causes of obesity. Bad sleep, stress, low testosterone/estrogen levels, low activity levels etc. These are often the most likely reason why you are gaining weight.
  • Don’t be afraid of artificial sweeteners, they are perfectly safe. Switching high sugar/high calorie foods for sweeteners can help you to cut calories and lose weight (but that’s a whole other article in itself!).

Hopefully this article has helped explain the effect of sugar on health and obesity, and why it isn’t the villain that it is painted as. You need sugar as part of a healthy diet, but you should also look at limiting your intake. 5-10% of your diet being made up of processed sugar is a good target to aim for (thanks to Precision Nutrition for that [7]) but this is just a rough guide and doesn’t include fruit, vegetables, grains etc.

Matthew Smith, BSc
Matthew Smith, BSc
Staff Writer & Fact Checker at DietProbe
Matthew Smith is a qualified sports scientist and registered exercise professional. He's a fitness and nutrition enthusiast and has a background in coaching and personal training.
Close Menu