There isn’t a single piece of food that does not contain calories. Fruits and veggies are not an exception.
The main carbohydrates in fruits come from two sources: glucose and Fructose. Their quantity varies, but usually, fructose prevails. After all, digesting the better part of the fruits makes your organism spend more calories than the fruits themselves actually contain.
The reason is that the process of extracting calories out of these foods is harder and more complicated, therefore the organism needs to spend a bit more time on them, thus, spending more energy than it receives. Of course, you shouldn’t eat only these foods, because it leads to loss of important nutrients and unwanted health issues.
Under the category of low calorie fruits we can place apples, raspberries, cherries, kiwi, peaches, strawberries, watermelons, apricots, mandarins, oranges, lemons, grapefruits. As far as high calorie fruits are concerned, we can mention bananas, pears, pineapples, melons, quinces.
|Fruit||Calories in every 100 gr|
When Should We Eat Fruits?
When we consume fruits in the morning, they provide us with a good amount of quick carbohydrates, vitamins, minerals, organic acids and normalise our pH balance. They give us water, whereas the fibres in their structure activate our lenient intestines, thus clearing them from all kinds of leftovers.
By eating fruits after physical training, such as jogging, yoga or exercising of any kind, we restore our glycogen balance throughout the fruit sugar. Their liquids also help to gain back the water we lost during training. In order to minimise the risk of getting fat when eating fruits, it’s best to do it in the morning, in the period until 12 o’clock, as well as 15 minutes after training.
Many people refuse eating fruits, because of fructose and the fear of gaining weight. Fructose in large amounts can overwhelm the glycogen reserves of the liver and form into body form. On the other hand, however, fibres and other nutrients bring more benefits, both for people who practice sports or don’t – the intake and the goals count. Fructose is the main carbohydrate in fruits. It can also be found in flower nectar, in plants’ seeds and, of course, in bee honey.
We can split carbohydrates into three different groups: monosaccharides, oligosaccharides and polysaccharides. While monosaccharides cannot hydrolyze, oligosaccharides and polysaccharides hydrolyze to simple sugars or monosaccharides. All carbohydrates are met in solid aggregate state in nature and have the same composition. Their molecules are built up of three elements: carbon, nitrogen and oxygen. Monosaccharides (glucose and fructose) are colourless crystal matter, water soluble and have a sweet taste. Their flavour is due to a high number of hydroxyl groups in their molecules. When they are heated, they melt down, caramelise and finally, carbonise by evaporating water.
Fructose looks more like glucose in terms of its physical properties. It has a sweeter taste and, unlike glucose, it dissolves in alcohol. Fructose has the same qualitative and quantitative composition and molecular mass, as the glucose. It’s molecular formula is С6Н12О6. Both can ferment under the influence of different enzymes. Depending on the kind of the fermentation, the end result can be lactic acid, acetic acid or acetone.
Fructose is twice sweeter than glucose. People with diabetes can absorb it easier, therefore they use it as a substitute.
Chemical Properties of Fructose
- Esterification – since fructose contains alcohol groups, it can undergo esterification, thus resulting in the respective esters.
- Fermentation – as a biochemical process happens together with carbohydrates under the influence of enzyme catalysts. It can be alcoholic, lactic acidic, acidic, methane, etc. Glucose and fructose ferment under the influence of cymasa until breaking down into alcohol;
- Acidification – it is typical just for monosaccharides amongst all carbohydrates as a chemical property. It can be explained with the too large the molecule of the non-saccharide polysaccharides. Both glucose and fructose have reductive properties.
Fructose creates a false sense of hunger, which leads to eating more food and, therefore, gaining weight. Its sweetness is 1.4 times higher than that of sugar, but it’s inappropriate for carbohydrate loading. The human organism burns it off easier than white table sugar, because it’s simpler, chemical compound. Fructose resorbs slower than glucose in the digestive system. A large part of it transforms into glycogen in the liver, which makes it more efficient to process and doesn’t require insulin for cell absorption. From a dietologist point of view, the higher sweetness is also important. You can flavour your meals and drinks with less amounts, which lowers the intake of carbohydrates. The glycemic index of the fructose is around 30, therefore it’s especially appropriate for people, suffering from diabetes.
A number of researches were made, proving that the fructose lowers the insulin susceptibility in the organism and influences the fats’ metabolism. These changes increase the risk of a cardiac-vascular problems. It’s been established, that when consuming fructose, the fats form predominantly around the inside organs, and less under the skin. According to doctors, the intake of large amounts of fructose in a combination with a high-caloric food rich in fats can lead to leptin resistance, thus complicating the maintenance of balance between the food intake and the organism’s energy needs. According to a few specialists, the fructose in plants cannot evoke leptin resistance in healthy people, no matter the amount of fruits they eat.
The fructose is a natural substitute of sugar. It’s fully absorbed by the organism and, like the table sugar, provides energy. In the most common case, it’s considered safe, but, unfortunately – caloric.
The Advantages of Fructose
- It is 30% less caloric than table sucrose.
- It influences on the levels of sugar in blood to a lesser extent, therefore it’s allowed for some patients with diabetes.
- Fructose is one of the few sweeteners, that have a conservative property, therefore used for making diabetic sweets. If you replace regular sugar with fructose, pastries remain soft for longer.
- It speeds up the breaking down of alcohol in the blood.
The Disadvantages of Fructose
- In larger amounts, it can increase the risk of cardiovascular diseases (the safe dose is no more than 30-40 gr a day).
- It influences indirectly gaining weight – it “misleads” the organism and creates a false sense of hunger;
- It speeds up the ageing processes – according to a study, conducted by Israeli scientist on mouses;
- The high fructose consumption can lead to a glucose intolerance and impaired insulin resistance. Both metabolic deviations are in close connection to insulin sickness.
- One can develop fructose intolerance, which results in intolerance to fruit juices, sport drinks or products, or sometimes even to fruits.
|Fruits (medium-sized)||Fructose (in grams)|
|250 gr. cherries||8|
|250 gr grapes||7|
|A slice of watermelon (around one kilogram)||12|
|250 gr berries||3|
|250 gr pineapple||7|
|250 gr blueberries||7|
|½ melon (½ kilo)||11|
|250 gr strawberries||4|
Fructose Influence on Our Bodies
The main organ for the metabolism of fructose is the liver. In it, the fructose transforms into derivatives of glucose and stores in the form of glycogen. The possibilities of the liver to transform the fructose are restricted, which is not good, because if large doses are taken, they can transform into fats. It’s typical for people with high level of lipids in the blood or insulin-resistant ones.
The level of fructose in the blood does not directly depend on the hormonal balance. This is one of the reasons that it does not evoke a quick influx of blood sugar. This is the biggest plus of the fruits, but, on the other hand, the large amount of fructose can cause fattening. There are more problems, connected with the intake of large amounts of fructose. One of them is the eventual inability to absorb it.
It remains unabsorbed in the intestines, whereas the consequences are bloating, gases, stomach ache. It’s considered, that 30-40% of people have similar problems. The more sensitive people, who are intolerant to fructose, the too much fruits can lead to gases, stomach ache and diarrhea.
The fructose does not cause separation of insulin and leptin – hormones, that help for suppressing the appetite, neither slows down forming of hormones, stimulating hunger. That’s why we say that the uncontrollable intake helps for gaining weight.
It’s wrong to consider, that you should stop eating fruits. All being said about fructose disadvantages is under a big “if” – if a person takes huge amounts. Even the daily consumption of fruits cannot cause energy disbalance, unless you overdo it or you happen to be one of the few people, suffering from the so-called fructose intolerance.
The Dangers of Corn Syrup
We are all aware how bad for our health refined sugar is and we even often call it “white death”. Scientists warn us, however, that fructose is not only unsafe, but can be even far more unhealthy. That’s because in practice, we take in the better part of the fructose from sugar substitutes, rather than from fruits. You can find the substitutes in the soft drinks, pastries and other products, containing sugar substitute.
Over the last 30 years, the producers have gradually replaced the regular table sugar as a sweetener in food or drinks with highly-fructose corn syrup, extracted from corn starch, after series of industrial processes. Its ability to increase the stability and sweetness of products makes it an important part of the production of many huge companies, whose products are consumed worldwide. What’s more, it contributes to browning pastries, therefore it’s used in cakes, biscuits, cereals.
Apart from all mentioned above, highly-fructose corn syrup is far cheaper to produce than other sweeteners, that’s why it’s preferred. Or, said in short – the fructose, sold in stores, is far from “fruit sugar”, extracted from fruits. It’s made in a complicated technological way out of spud or corn starch with additional chemical treatments. Under the form of a sweetener, it has long been present in many of the foods and drinks we consume in a daily basis.
People often ask the question: “If I want to reduce my body fat, do I have to restrain from fruits?”
Fitness lovers and dieticians stay firmly behind the position against fruits, if you are on a diet to reduce your weight. Others use those foods frugally. There’s no right or exact formula for fruit consumption – the bottom line is, you can and it’s beneficial to eat fruits together with their fruit sugar, but in normal amounts, keeping a proper food and sports regime!