fructose… victim or villain?

  • Fructose (a.k.a “fruit sugar”) is used to sweeten many modern processed foods due to its sweetness and low cost.
  • On the plus side, fructose has a lower glycemic index value than glucose and does not require as much insulin to metabolise.
  • On the downside, fructose is processed directly by the liver, does not trigger appetite signaling hormones such as leptin, and in excess can lead to increased triglycerides and LDL, and can lead to fatty liver.
  • If we focus on nutrient dense foods that don’t spike blood glucose levels will mean that we largely avoid empty calories, including foods high in fructose.

it all started when…

Not so long ago people with diabetes were advised to use fructose rather than glucose as the sweetener of choice.[1]  

More recently though the reputation of fructose has become tarnished.

Let’s look at what happened and what it means for us now.[2]

the good

At first glance, fructose appears to have a number of positive qualities.

  1. With a Glycemic Index (GI) value of 19, fructose raises blood glucose less than other sweeteners such as sucrose (table sugar) (GI = 66) or pure glucose (GI = 100).[3] [4]
  2. Fructose requires less insulin to metabolise than other carbohydrates. [5]
  3. High fructose corn syrup is cheaper than other sweeteners (though this is largely due to government subsidies).[6]
  4. Calorie for calorie, fructose is sweeter than sucrose so you don’t need to use as much to get the same effect.[7]

the bad

These days the list of negatives attributed to fructose is increasing.

  1. Excess fructose increases triglycerides and LDL cholesterol more than glucose.[8]
  2. Excess fructose can lead to fatty liver, insulin resistance and type 2 diabetes.[9] [10]
  3. Fructose does not trigger appetite the signalling system hormones insulin and leptin so it is easy to overeat foods sweetened with fructose.[11]
  4. Fructose over consumption may be at the heart of metabolic syndrome which has also been linked to a wide range of cancers.[12]

foods highest in fructose

The foods highest in fructose are listed below.  With soft drinks at the top of the list, it is also interesting to note that a range of naturally occurring foods are not far behind.

food % calories from fructose
cola 58%
agave 52%
Sprite 51%
apple sauce 50%
apple juice 50%
honey 50%
salad dressing (fat-free) 48%
apples 45%
pears 43%
grapes 42%
ginger ale 42%
mango nectar 42%
dates 41%
Powerade 40%
pineapple 40%
lemonade 40%
watermelon 40%
raisins 36%

For our ancestors, high fructose, low satiety fruits would have been an effective way to store some extra fat in preparation for winter.

In our modern environment though, foods high in fructose are available all year round and can easily lead to excess consumption of “empty calories”.

Fruits do contain vitamins, however most fruits are typically not as nutrient dense as vegetables.  Avocados and olives are the only fruits that routinely make it into the lists of nutrient dense foods.


High Fructose Corn Syrup (HFCS) was developed in the 1950s and was incorporated into our diet in processed foods between 1975 and 1985.[13]  HFCS now represents more than 40% of the caloric sweeteners added to foods and beverages and is the sole source of sweetener in soft drinks in the USA.[14]

The low nutritional value of soft drinks combined with the fact that they are easily over consumed makes for an ominous combination.


fructose, glucose, sucrose, starch…  does it really matter?

There has been a lot of discussion about the perils of added sugar (e.g. That Sugar Film and I Quit Sugar) as well as dire warnings about high fructose corn syrup.  However in the end I’m not sure there is a big difference.

Fructose is processed directly by the liver and converted to triglycerides and LDL, largely without insulin.

Glucose that isn’t burned immediately raises blood sugar and is mopped up by insulin and stored as body fat and triglycerides in the blood.

So in the end, excess carbohydrate, whether it comes from fructose or glucose, ends up as stored body fat or fat in your blood stream (i.e. cholesterol).

The table below shows a comparison of the types of sugars contained in a number of foods along with their nutrient density score (note: a ND score of zero corresponds to the average of the foods in the USDA foods database, less than zero means that it’s less nutrient dense than average).

food % calories from carbs % starch % maltose % glucose % fructose Nutrient Density / cal
cola 100% 0% 0% 42% 58% -0.43
apple juice 95% 0% 15% 22% 49% -0.37
sweet potato 84% 31% 17% 3% 2% -0.11
white bread 79% 61% 3% 3% 3% -0.03

In his Perfect Health Diet Paul Jaminet says:

“A nourishing, balanced diet that provides all the required nutrients in the right proportions is the key to eliminating hunger and minimising appetite and eliminating hunger at minimal caloric intake.” 

While cola and apple juice may have the highest percentage of calories from fructose they also have the lowest nutrient density values.  So if you’re not worried about the carbs it’s going to be better to have the sweet potato or the bread from a nutrient density point of view.

Although at the same time you’ll notice that the sweet potato and bread both have less nutrients per calorie than the average of all the foods analysed.  There are a going to be better food options if you’re interested in nutrient density and / or blood glucose control.


the bitter truth

While Robert Lustig has drawn a parallel between the toxic effects of alcohol and fructose on the liver,[15] it is not entirely clear whether the overall effect of fructose is actually worse than any other form of carbohydrate, particularly if not eaten in excess.[16]

If you are insulin sensitive and have excellent blood glucose control should you avoid all apples and grapes just because they contain fructose?  I’m not sure.

Perhaps naturally occurring fructose with the fibre packaging it came in is not going to be such a big deal.  A quick check with a blood glucose meter will tell your whether your body can tolerate that banana or orange.

What we do know is that substituting carbohydrates with fat, particularly omega 3 (fish) and oleic acid (olive oil),  will provide positive outcomes in terms blood markers such as HDL and LDL (see the Good Fats, Bad Fats).

Even the gurus though are divided on the topic of fructose.  Dr Richard Feinman says:

“Dietary carbohydrate restriction remains the best strategy for obesity, diabetes and metabolic syndrome.  The specific contribution of removal of fructose or sucrose to this effect remains unknown.”[17]

fructose and the food insulin index

If you have read much of my blog you’ll know that I’m interested in using the food insulin index data to refine our understanding of our insulin response to food.  So what does the fact that fructose requires less insulin than glucose mean for predicting our insulin response to food?

As shown in the plots below, our insulin response to food is loosely related to carbohydrate content and the glycemic load of our diet.[18]   When we look a little closer though we see that high protein foods require insulin while fibre containing foods require less insulin than we might have expected.


Once we account for the effects of fibre and protein we are better able to predict our blood glucose and insulin response to food.  However even after we account for fibre and protein the outliers that require less insulin than we might have anticipated seem to be foods higher in fructose (e.g. Coke, corn, raisins, bananas, and oranges).


We know that fructose requires less insulin than other carbohydrates.  Once we account for this fact the correlation improves even further.  The high fructose foods move back towards the trend line.  The best correlation is achieved when we assume that 72.5% of fructose does not require insulin.  This aligns with the observation that fructose has a lower GI and our understanding that fructose can be converted to glucose via gluconeogenesis.


useful for diabetes or just a ‘fun fact’?

For people with type 1 diabetes this additional understanding of the way fructose affects insulin demand could be used to more accurately calculate insulin doses.  Rather than simply assuming that all carbohydrates require insulin we can better predict the insulin demand by considering protein, fibre and fructose.

However, in practice this is probably a little over the top.  The simplest approach for people trying to manage insulin and blood glucose levels is to simply avoid or limit non-fibre carbohydrates, including fructose containing foods.

what does this it all mean?

But what does this mean for the rest of the population who do not routinely pay attention to their blood glucose levels?


I think the take home of all this is that if we focus on nutrient density and maximising nutrient dense foods the foods that are highest in simple carbohydrates (like fructose, glucose and sucrose) will fall off our shopping list.

Fructose, glucose, sucrose, maltose or starch?  Which one is worse?  Personally, I’m not sure, but I think  if you focus on nutrient dense foods that normalise your blood glucose the question largely becomes irrelevant.

Excess low satiety empty calories are a disaster regardless of their source.























zucchini and feta fritters

This recipe for zucchini and feta fritters is from All Day I Dream About Food.

It’s a great gluten free low carb option and an good alternative if you want a change from different combinations of eggs, bacon or spinach.

The spices (marjoram and oregano) and seeds (coconut and flax) provide solid levels of fibre as well as vitamins and minerals.

Chrome Legacy Window 28122015 55727 PM.bmp.jpg

net carbs

insulin load carb insulin fat protein fibre
6g 14g 40% 78% 12%









the most ketogenic foods

Ketosis occurs when the body’s glucose stores and insulin levels are low and the body increases its use of fat for fuel.  The insulin load of a food is related to its carbohydrate, protein and fibre content.

Calculation of the percentage of insulinogenic calories enables us to prioritize of foods with a lower insulin demand which will lead to nutritional ketosis and improved blood glucose control.


Listed below are the most ketogenic foods based on the percentage of insulinogenic calories (excluding fats and oils).  Also included in the tables below are:

  • the nutrient density score (ND) ,
  • net carbohydrates or insulin load which will be of interest if you are insulin resistant and / or managing blood glucose levels, and
  • energy density (calories/100g) which will be of interest if you are watching your weight.


food ND % insulinogenic net carbs/100g calories/100g
chicory greens -0.28 27% 1 28
artichokes 0.71 33% 3 54
chives 0.21 34% 1 37
cilantro -0.46 36% 1 28
parsnip 0.64 38% 7 76
turnip greens 1.15 39% 1 37
banana pepper 0.19 41% 3 39
spinach -0.54 41% 1 29
seaweed (kelp) 0.78 43% 4 50
beets 0.28 44% 4 48
mustard greens 0.19 45% 2 30
collards 0.36 46% 2 40
mung beans 0.63 46% 1 26
alfalfa (sprouted) -0.54 46% 1 31
asparagus 0.94 46% 2 27
snap green beans 0.64 47% 4 40
pickled cucumber -0.87 48% 1 13
celery 2.67 49% 1 17
parsley 0.11 49% 3 44
radishes 0.66 50% 2 19
lettuce 1.10 52% 2 17
bamboo shoots 0.74 52% 3 28
endive -0.62 52% 2 20
cabbage 0.67 53% 3 30
arugula -0.03 54% 2 31
jalapeno peppers 0.54 54% 4 35
Brussels sprouts 0.19 54% 5 52
carrots 0.14 55% 5 39
cauliflower -0.61 57% 3 28
okra 0.92 57% 4 37
rhubarb 1.22 57% 3 21
broccoli 1.06 57% 4 42


food ND % insulinogenic net carbs/100g calories/100g
olives 0.00 15% 3 90
avocado 0.01 18% 5 131

nuts and seeds


food ND % insulinogenic net carbs/100g calories/100g
macadamia nuts 0.12 5% 5 769
pecans 0.15 5% 4 762
coconut milk 0.03 8% 4 246
Brazil nuts 0.09 9% 4 704
pine nuts 0.15 11% 9 647
coconut meat 0.09 11% 16 703
flax seed 0.08 12% 2 568
walnuts 0.10 15% 7 683
hazel nuts 0.10 16% 15 692
chia seeds 0.10 16% 8 511
tahini 0.16 16% 13 633
almonds 0.11 16% 15 652
sesame seeds 0.12 18% 14 603
sunflower seeds 0.18 20% 11 491
cashew nuts 0.11 22% 24 609
pistachio nuts 0.15 23% 19 602

 dairy and egg


food ND % insulinogenic insulin load  (g/100g) calories/100g
butter 0.11 0% 1 734
cream 0.10 5% 5 431
sour cream 0.12 9% 4 197
cream cheese 0.15 10% 8 348
Limburger cheese 0.17 18% 15 327
brie cheese 0.15 19% 16 334
egg yolk 0.18 19% 15 317
muenster cheese 0.16 20% 18 368
Camembert cheese 0.17 20% 15 299
Monterey Jack 0.16 20% 19 373
blue cheese 0.17 20% 18 354
feta cheese 0.17 22% 14 265
mozzarella 0.15 23% 18 318
ricotta cheese 0.09 25% 11 174
Greek Yogurt 0.02 27% 9 130
whole egg 0.17 29% 10 138



food ND % insulinogenic insulin load  (g/100g) calories/100g
caviar 0.28 32% 22 276
herring 0.24 34% 18 210
sardine 0.22 36% 18 202
swordfish 0.28 41% 17 165
anchovy 0.31 42% 21 203
rainbow trout 0.27 43% 17 162
mackerel 0.25 45% 17 149
sturgeon 0.23 47% 15 129
tuna 0.27 50% 17 137
squid 0.16 50% 21 170
salmon 0.26 50% 15 122

animal products


food ND % insulinogenic insulin load  (g/100g) calories/100g
foi gras 0.12 11% 13 459
beef ribs 0.12 13% 12 349
pepperoni 0.16 14% 17 487
frankfurter 0.11 14% 11 322
pate 0.13 16% 13 315
chorizo 0.15 17% 19 448
duck (with skin) 0.13 17% 14 331
salami 0.13 18% 12 258
lamb 0.15 24% 18 308
veal brain 0.09 25% 8 133
bratwurst 0.05 25% 11 171
polish sausage 0.10 26% 17 259
beef steak 0.16 28% 21 305
salami 0.11 29% 12 166

Depending on your goals, the following lists may also be of interest:

kale with chorizo and eggs

This recipe comes from the Real Meal Revolution which contains a wide range of excellent low carb and nutrient dense meal options as you would expect from a recipe book with Tim Noakes at the helm).

The new Raising Superheroes is a “real food” cookbook with a range of real food recipes to provide parents with scientifically supported advice and delicious recipes to raise the healthiest, brightest kids possible.

The analysis below shows that the combination chorizo, egg, spinach and butter does a really nice job of covering off on a wide range of vitamins, minerals, amino acids and fatty acids.

Chrome Legacy Window 9062015 55841 AM.bmp

Chorizo has an excellent protein score, minimal carbs and a reasonable array of vitamins and minerals.  It’s a processed meat, so get the good stuff if you can.

Chrome Legacy Window 28122015 45227 PM.bmp.jpg

Eggs are hard to beat when it comes to a complete protein and also have an excellent array of vitamins and minerals.  Try to get eggs from free range happy hen who get to see the sun and eat some bugs and grub for bonus points.

Chrome Legacy Window 28122015 45551 PM.bmp.jpg

And kale does a great job of filling out the vitamins and minerals while still having a reasonable protein score.

Chrome Legacy Window 28122015 45758 PM.bmp.jpg

As you can see from the screen grab from Nutrition Self Data, spinach has an even higher nutrient score, higher protein score and more fiber.  A win for both nutrient density and blood glucose management.

Chrome Legacy Window 28122015 50042 PM.bmp.jpg

carbs insulin load carb insulin fat protein fibre
2g 14g 12% 79% 18% 2g