Carbohydrates are one of the three macronutrients that make up your diet; the other being fat and protein.
Its prime use is to serve as a fuel or energy source (4kcal/gram) but it is not considered as an essential nutrient.
Chemically they are made up of saccharides- a group of sugar, starch, and cellulose. Carbs are classified as:
- Simple carbohydrates- Made up of one saccharide unit (monosaccharide)
- Complex carbohydrates- Made up of multiple saccharide units (polysaccharides)
Another classification made with respect to nutrition is:
- Sugars - These are short chains of carbohydrates that are sweet to taste and extracted from fruits eg: glucose, fructose
- Starch - They are a long chain of glucose which are broken down by our digestive system to simple glucose
- Fibre - They are complex carbohydrates which we can't digest but are of use to the gut bacteria
This not so essential nutrient finds its use in following body functions:
- Energy supply- Glucose is used directly by muscles and brain cells as fuel. Fructose and galactose is converted by our liver to glucose.
- Energy storage- Glucose that is not required as instant energy is stored as glycogen in the liver and muscle. When these reserves are full, glucose is stored as fat.
- Building macromolecules- Glucose is used to make up basic units of RNA, DNA, and other vital macromolecules.
- Sparing proteins- When adequate glucose is unavailable, protein is broken down to prepare glucose. When the required levels of glucose are present, protein is preserved.
- Sparing fats- When adequate glucose levels are present, they signal the hormone insulin to make the cells use glucose instead of fat as energy
Note: So its clear that carbohydrates’ sole function is to provide energy and its deprivation can lead to breakdown of not only fats but also proteins. So a moderate carbohydrate intake should be appropriate for weight loss.
Good v/s Bad carbs: Which one causes weight gain?
In simple terms, good carbs are the ones that are healthy for us and bad carbs are the ones that make us gain weight. Good carbs are the ones that are directly harvested from the farms and consumed while bad carbs are the factory produce which is over processed and over-refined.
Here are few benefits linked with good carbs and which the bad carbs lack:
- They provide low to moderate levels of calories.
- They are satisfying and control our appetite.
- They are rich in vitamins and minerals.
- They are low in saturated fat and cholesterol and no trans fat.
- They are a rich source of natural fibre.
- They are devoid of refined sugar.
You might be wondering that if you get all these benefits from other components of your platter then why to cut down on bad carbs. This is how it works. Glycemic index a system that classifies carbohydrates according to the effect they have on our blood sugar levels on ingestion.
Good carbs like whole oats have a low glycemic index as the fibre and nutrients allow slow release and absorption of glucose. Bad carbs like white bread have a high glycemic index which gives rise to a sudden surge of blood sugar. This upsets insulin activity and triggers hunger and craving for high carb foods.
So which are the good carbs?
- Whole grains like oats and brown rice
- Whole fruits
And the bad carbs?
- Sugar-sweetened beverages
- Refined grains
- Added Sugars
- Ice creams, pastries, and similar items
- White bread and French fries- processed carbohydrates
Had I understood this concept a little before I would opt for a bowl of whole oats cereals rather than FROOT loops.
Note: Good carbs don’t cause weight gain and they are natural sources of carbs. Bad carbs are the processed carbohydrates and the added sugar.
How Carbohydrates Cause Weight Gain?
The whole controversy on carbohydrates and weight gain started this way.
Initially low-fat diets were recommended on the grounds that fats make you fat.
Oddly still people didn’t seem to lose weight.
So the blame was then placed on carbohydrates.
Carbohydrates do cause weight gain but that is applicable only to refined carbohydrates like pasta, white bread, table sugar, and added sugar.
Refined carbohydrates cause weight gain in two ways:
1.Blood sugar surge
Glycemic load is the number by which particular food item raises the blood sugar. Refined carbohydrates have a high glycemic load.
To stop such high levels of sugar from circulating in the blood insulin levels as increased to facilitate the use of glucose as energy. Else this glucose is stored as glycogen and excess is stored as fat.
Now insulin has one more action. It is a fat storing hormone.
It inhibits the breakdown of fat cells and stimulates the production of fats. This leads to some nasty fat accumulation especially in the form of belly fat.
Increased refined carbohydrate consumption leads to insulin resistance where cells fail to respond to the activity of insulin. Increased insulin levels leads to fat accumulation.
2. Addiction and cravings
You never seem to get over sugar-laden stuff, chocolates and ice creams right.
Well, it's your brain at play.
Eating sweet items gives a sense of pleasure and a rewarding feeling as your brain secretes chemicals like dopamine and serotonin.
It makes you feel good and you crave for it. And the rule in excess of anything leads to weight gain.
So overeating carbs is an addictive cycle which eventually causes weight gain.
So not all carbohydrates lead to weight gain. The culprit is refined carbohydrate present in processed foods.
Note: Refined carbohydrates cause weight gain by disturbing insulin activity and causing an addiction to processed carbs leading to overeating.
How does Carbohydrate Help in Weight Loss?
If you select the right quality of carbs, cut down the bad carbs and determine a number of carbs that would suit your body, then you can lose weight despite eating carbs.
Resistant starch is good for weight loss
Resistant starch is a type of starch that acts like insoluble dietary fiber.
Like regular carbohydrates, it does not get digested and broken down into glucose. It acts as a laxative and improves colon health.
Most carbohydrates are a good source of resistant starch such as raw potatoes, legumes, sweet corn, oats, barley, banana etc.
There are a few ways by which resistant starch can mediate weight loss:
- It improves digestion and activity of gut microflora.
- It prevents a steep rise in blood sugar levels and improves insulin sensitivity.
- It promotes satiety and reduces subsequent calorie intake.
Supplemental resistant starch extracted from potato is available but we are not really sure whether the external addition of starch to the diet will cause any significant effect on your weight. Natural sources are a better option.
What does this mean? Resistant starch acts like dietary fibre and helps control appetite and improve colon health.
It controls appetite
Carbohydrates with a low glycemic index have a beneficial effect on blood sugar. Due to the slow release and absorption of glucose, you tend to feel less hungry.
Also, the dietary fibre and resistant starch present in carbohydrate sources control appetite.
High carbohydrate diets are proven to promote a feeling of fullness after meals and have a beneficial effect on body weight.
A study was conducted to evaluate the effect of indigestible carbohydrates on appetite and glucose metabolism.
Individuals were given boiled barley kernels or white bread for evening meals.
The boiled barley kernels served as a good source of indigestible carbohydrates and they enhanced glucose metabolism and reduced blood sugar levels better than white bread.
Also, the barley kernel was found to reduce appetite until the subsequent morning, which is around 10-16 hours! Energy intake at lunch was reduced.
Inulin and Beta- glucan are fermentable carbohydrates found in many grains. Both of these prevent body weight gain by increasing metabolism and control hunger by acting on brain cells that control appetite.
Whole grain food items control appetite better than refined carbohydrates.
In a clinical trial the effect of cereal based bread and white bread was compared on appetite.
The cereal based bread was made from wheat, oat and spelt flour, dried fruits and was enriched with protein and fibre.
Consumption of this cereal bread reduced prospective intake and enhanced satiety more than white bread.
Reduction in blood glucose levels and ghrelin-‘hunger hormone’ was observed.
Physical structure of the carbohydrates also make a difference in influencing appetite which is why it is recommended to have whole fruits, grains and vegetables.
An experimental study demonstrated that whole lentils were more effective than blended lentils in controlling appetite. The effect lasted for 4 hours which a good deal of time to burn calories.
What does this mean? Good carbohydrates like whole fruits, vegetables and whole grain food items are rich in fibre. Hence they satisfy hunger and control appetite unlike refined carbohydrates.
It influences blood sugar and insulin levels
If you have read the previous sections you must have understood how carbohydrates can cause blood sugar spikes leading to weight gain.
Interestingly this is not the case with every carbohydrate source.
Whole grain cereal products lower blood sugar and favourably regulate insulin responses. Beta glucan found in oats and barley prevent a rapid rise in blood glucose after meals.
Researchers suggest that this effect is more pronounced in intact grains than processed foods.
They recommend that 4g of beta glucan and 38-80g of carbohydrate can effectively control blood sugar.
A clinical trial was conducted to evaluate the effect of consumption of barley tortillas varying in fibre and starch content on post meal glucose levels.
The starch and fibre content in the tortillas did not seem to affect glucose and insulin levels but tortillas containing high levels of beta glucan lowered blood glucose and insulin response and influenced satiety.
Fruits are another carbohydrate source that can have a beneficial effect on glucose.
White bread eaten with berries lowers blood glucose and insulin response. Regular raisin consumption reduces blood glycemic load caused by processed snacks.
What does this mean? Good carbs have a low glycemic index: they do not raise your blood sugar alarmingly which in turn avoids the sugar roller coaster and weight gain.
Low levels of carbohydrate improve exercise induced weight loss
Carbohydrates and fats are the principal sources of fuel for muscles. Research documents the use of carbohydrate to improve exercise performance.
Lack of carbohydrates forces the body to use an alternative source of fuel- fat. This leads to fat burning.
A number of studies show that low carb diets initiate fat oxidation and maintain exercise performance.
They also improve weight loss outcomes by raising energy expenditure and get rid of the stubborn belly fat.
What does this mean? Studies show that supplementing your body with low levels of carbohydrates increases exercise induced weight loss.
Carbs have a beneficial effect on gut microflora
Our intestines are made up of healthy bacteria that aid in digestion.
But when things go wrong with them, they tend to harvest more energy, promote fat deposition and cause inflammation.
Many studies talk about the relation between gut microbes and obesity.
Dietary fibres present in oats, barley, chickpeas and other carbohydrate sources restore the health and activity of the gut microflora, serving as prebiotics.
What does this mean? Carbohydrates improve colon health and good gut microflora has been lined to reduced risk of obesity.
Low carb diets for weight loss
Low fat diets have been replaced by low carb diets.
The absence or reduced levels of carbohydrates force your body to utilise fat as fuel.
This also reduces your insulin levels and moves your body to a state known as ‘ketosis’ where fats are burnt at a high rate. Here are a few benefits linked with low carb diets:
- They lower appetite.
- They maintain weight loss.
- They reduce water weight.
- They reduce carbohydrate addiction
- They support calorie burning
However ,some critics have a different view. Many arguments proposed against this diet are that they increase the risk of binge eating, disturb the mood, cause dizziness and weakness and increases intake of cholesterol and saturated fats.
We would always a recommend a healthy diet with moderate amounts of all dietary components.
Note: Low carb diets act by forcing the body to burn fats as a source of energy.
How much Carbohydrates Should you Consume while Aiming for Weight loss?
The recommended dietary allowance for carbohydrates is 130g/day for adults and children and this is typically to meet energy requirements.
The median intake of carbohydrates is approximately 220 to 330 g/d for men and 180 to 230 g/d for women.
Your requirements for carbohydrates depend on your physical activity and your metabolism. Research on low carb diets recommend 20-50 grams of carbohydrates a day.
However, we would suggest a range of 40-60 grams to ensure a balance of nutrients.
Note: Eat 40-60 grams of carbohydrates while attempting to lose weight. For a healthy person 100-150 grams per day is fine.
Should carbohydrate alone be blamed for weight gain?
No. Firstly it’s the refined carbohydrates that are to be blamed.
Secondly, it also depends on your body. If you are an active person, you can easily metabolise extra calories but if you are the sedentary person you are likely to gain weight.
If you suffer from diabetes and metabolic syndrome it is advisable to consume a low carbohydrate diet.
Sometimes after dieting, if you start eating carbohydrates you temporarily tend to gain weight which is at times mostly water weight and glycogen storage.
And obviously, if you are eating an excess of refined carbs, you will gain weight.
Note: No, carbohydrates don’t cause weight gain unless you are overeating or suffer from a metabolic disease.
Carbohydrates though considered a non essential nutrient, seems like a very essential nutrient to me as it is the most readily accessible form of energy.
Bad carbs are the evil ones who lead to weight gain and other metabolic diseases.
If you choose healthy sources of carbohydrates such legumes, whole grains, vegetables, fruits then you don’t need to worry about your weight as they definitely don’t lead to an accumulation of extra pounds.
However avoid processed foods like white bread, pasta and especially added sugars.
Drop the myth of carbohydrates causing weight gain and bring home the energy packed nutrients.