Weight loss paraphrases into calorie restriction and exercise. Calorie restriction is mediated by various diets and perhaps one of the most controversial diets is low carb diet.
Origin of low carbs diet dates back to 1864, when William Banting wrote his famous Letter on Corpulence that suggested four meals of meat or fish per day and strictly avoid starch or sugary food items.
Banting suffered from obesity and hearing loss caused by fat compressing his inner ear. After following a low carb diet, he lost weight and his hearing improved.
A few decades ago, health authorities recommended low fat diets for it was believed that ‘fat makes you fat’. Surprisingly despite of eliminating fat from their diet, people still seemed to gain weight.
Since diet was low in fat but high on carbs, it was reasoned that carbohydrates caused weight gain.
Hence the new diet plan emerged-low on carbohydrates, high on fats and proteins.
How carbohydrates cause weight gain?
Carbohydrate is one of the three dietary components that we consume to ensure a balance diet. It is not considered as an essential nutrient but it is the preferred form of energy (4kcal/gram) for most of our body cells.
Carbohydrates are of three types: sugar, starch and fibres. There exists a term know as glycemic index- the effect a food material has on your blood sugar. The good carbs are low in glycemic index that is they do not cause sudden spike in blood sugar.
How is this related to weight gain!? Sudden rise in blood glucose elevates the levels of insulin because insulin lowers blood glucose by using it as energy or storing it. Excess glucose is stored as fat.
Also insulin has ‘fat producing’ properties; therefore more insulin means more fat.
But good carbs are low in glycemic index , like whole grain has a number of other nutrients such as vitamins and fibre which allow slow release of sugar.
The bad carbs such refined sugar, refined grains, processed food and added sugars cause the weight gain.
Note: Not all carbohydrates cause weight gain. Refined sugar, added sugar, processed foods and refined grains can cause weight gain by disturbing activity of the hormone insulin.
What is a low carb diet?
Many versions of low carb diets (LC diets) exist such as Atkins New revolution diet, South Beach, Dukan diet etc.
What differentiates LC diets from high protein diets is that carbohydrates constitute 10-30% of the energy which gradually increases with time and has relatively high amounts of fat.
Most diets constitute three or more stages. The earliest stage lasts for 2 weeks and permits the least amount of carbohydrates. The middle stage is weight loss stage and the number of carbohydrates consumed is increased and maintained till desired weight loss is achieved.
During the final stages, carbohydrates are increased till weight loss stops or weight gain begins and again the amount of carbohydrate is reduced still weight stabilizes.
The number of carbs allowed varies with every plan but on an average the range for weight loss is 25-45 grams per day. A research study investigating carbohydrate restrictions for diabetics suggested the following ranges:
- Moderate carbohydrates: 130-225 g
- Low carbohydrate: under 130 g
- Very low carbohydrate: under 30 g
The amount of carbs consumed once ideal weight is achieved depends upon age, gender and physical activity of the individual. Dr. Atkins recommends around 45-100 grams of carbohydrates for healthy weight.
Speaking of carbs, it is the net carbs that are to be taken into consideration. Net carbs is the total number of carbohydrates minus the amount of fibres and sugar alcohols.
These two categories are not considered since they do not significantly impact insulin levels. Most low carb diets recognize that all carbohydrates are not bad and incorporate foods with lower glycemic index.
How low carb diets help in weight loss?
As mentioned previously, carbohydrates are the most preferred form of energy. So when you lower your carbohydrate intake, you are stimulating your body to derive energy from alternative sources.
And your body chooses fat and burning fats means weight loss. Here are the scientific reasons as to how low carb diets aid in weight loss.
1.It raises metabolism
Low carbohydrate diets have a metabolic advantage and studies show favourable outcomes on energy expenditure. A study was conducted to investigate the effects of low fat, low glycemic index diet and very low carbohydrate diet on weight maintenance.
Low carbohydrate diet showed the least reduction in metabolism compared to other diets and stimulated weight loss.
This improvement in metabolism by low carb diets occurs due to two reasons:
- Gluconeogenesis- This is a process which occurs in absence of carbs. The body starts producing glucose from proteins and expends around 400-600kcal. Low carb diets favour gluconeogenesis.
- High protein content: Low carb diets are high in protein and high protein diets are known for boosting metabolism.
What does this mean?
Low carb diets stimulate healthy metabolism which supports efficient use of fuel.
2.It lowers insulin levels
Sugar and insulin levels are interdependent. When our blood sugar level rises, insulin is immediately released to reduce the circulating levels of sugar and to promote utilisation of glucose as energy or store it as a reserve for future.
Insulin supports formation and storage of fats. It converts fructose (a type of sugar) into fat. Increased refined carbohydrate consumption leads to a condition called insulin resistance- the cells stop responding to action of insulin.
So instead of utilising glucose as energy, it is stored as fat leading to weight gain.
Low intake of carbohydrates means low insulin levels which means utilisation of fats instead of glucose. A study was conducted wherein obese individuals were given ‘Atkins’ LC diet for 24 weeks.
Individuals lost on an average 9.7 kg at the end of the study and improvement in glucose metabolism and insulin sensitivity was observed in week 12 and 24. Insulin resistance can increase risk of cardiovascular diseases.
Inclusion of whole grains, fruits and vegetables and lean sources of animal proteins ( all these constitute a low carb diet) reduces insulin resistance.
What does this mean?
Low carb diets regulate insulin levels to a healthy state which reduces fat accumulation and storage.
3.It burns fat by shifting your body into a different metabolic state
Insulin helps derive energy from carbohydrates. In scarcity of dietary carbohydrate, reduced insulin levels leads to reduced fat accumulation.
After a few days of drastically reducing carbohydrates, glucose reserves become insufficient for fat oxidation or functioning of the central nervous system.
So the brain starts looking out for alternative sources of energy and in response the liver starts producing ketone bodies from fatty acids. This metabolic state is known as ketosis.
This condition helps in suppressing appetite, boosting metabolism and preventing fat formation and storage.
However ketosis should not be consumed with ketoacidosis. Ketosis is a normal metabolic condition while ketoacidosis is characterised by abnormally high concentrations of ketones and it can develop into a life threatening situation.
What does this mean?
Low carbohydrate diets stimulate your body to burn fat by switching the body’s metabolic state to ketosis.
4.It keeps you satisfied and curbs hunger
LC diets promote postmeal satiety and curb hunger. So it is different from other calorie restricted diets which make you feel hungry and are difficult to adhere to.
Following mechanisms indicate the science behind appetite suppressing properties of LC diet:
- Diet volumetrics: LC diet includes consumption of vegetables, fruits and whole grains which are low on energy but make you feel full.
- High protein content: Diets rich in protein promote satiety and reduce hunger.
- Ketone bodies: In extremely low carbohydrate intake, ketone bodies are formed which suppress appetite.
- Direct alteration of appetite hormones: Hunger hormone (Ghrelin) and satiety hormone (Leptin) are favourably altered to reduce appetite.
What does this mean?
Low carb diets suppress appetite owing to their high protein and fat content.
5.It helps get rid of water weight
When glucose is not used readily as a source of energy, it is stored in another form known as glycogen. Stored glycogen in muscles and liver tends to bind some water which contributes to water weight.
So when you cut down on carbs, body starts utilising glycogen reserves thus flushing out the water with it. That is why initially that is around for the first week of low carb diet, individuals tend to lose water weight.
Most people use this as an argument that low carb diets lead to only loss of water weight, however that is only the initial phase, later fat loss is also experienced. And anyways water weight is not of any use either, so its loss counts as benefit.
What does this mean?
Initial weight loss with low carb diet is loss of water weight.
6.It helps in dumping belly fat
If there is one place where most people would like to get rid of their fat from, it is the dangerous abdominal fat. Belly fat comes under the harmful visceral fat which increases the risk towards metabolic diseases and diabetes.
An 8 week study comparing the effect of low and high carbohydrate diet on cardiovascular risk factors demonstrated a significant weight and abdominal fat loss in volunteers with low carb diet than high carb diet.
A research study conducted in University of Alabama, Birmingham demonstrated a 4.4.% loss of fat mass in individuals consuming low carbohydrate diet and loss was primarily of abdominal fat tissue.
This study also reported loss of intramuscular or arm fat.
What does this mean?
Low carb diet aids in getting rid of abdominal fat and trunk fat in a short time period.
Health benefits of a low carb diet
Apart from weight loss, LC diets show improvements in features of metabolic syndrome like cholesterol, blood pressure and blood sugar levels.
The healthy fat present in LC diets brings about improvement in the healthy cholesterol levels. The ketone bodies produced in response to a very low carbohydrate diet are beneficial in treating brain disorders.
What to eat and what to avoid in low carb diets?
Here is a general list of foods to eat and not to eat that can aid you in planning your low carb diet:
May be eat
Avoid/ Never eat
Healthy fats (Coconut oil, cod liver oil)
|Tubers (Potato family)
Gluten free grains like rice and oats
Gluten grains like wheat, barley
Refined grains and products (Bread and pasta)
Added sugar (sweetened beverages, sodas, ice cream etc)
Here is a list of popular low carb diets that you can follow in case you are too lazy or confused on how to design your own LC diet:
- Atkins diet
- Carbohydrate Addict’s diet
- Palaeolithic diet
- Diet Cure
- Eat Fat Get Thin diet
- Ketogenic diet
- Life without Bread
- Protein Power diet
- Schwarzbein Prinicple
Low carb v/s Low fat diets
A clinical trial studying the effect of low carb (‘Atkins’) diet on obesity was carried out for a period of 1 year. Participants taking LC diet lost 7.3% of their total body weight while those on low fat diet lost around 4.5% of their weight.
The difference in weight loss was significant in months 3 and 6 but not at the end of the study.
A 6 month study comparing LC and LF diets in severely obese individuals demonstrated three times more weight loss in those taking LC diet (5.8 kg) than those consuming LF diet (1.9kg).
LC diet has proven to cause twice the weight loss than that brought about by a calorie restricted low fat diet.
Majority of the studies support the idea that low carbohydrate diets cause better weight loss outcomes than low fat diets and also bring about improvements in metabolic parameters.
Concern regarding low carb diets
A few research evidences express some safety concerns regarding low carbohydrate diets. First one being, during the initial phase the carbohydrate intake is so low that it can be considered inadequate for body functioning.
That’s why initially people experience fatigue, lack of energy, dizziness, irritability and light headedness when they shift to LC diet.
This phase is known as low carb flu. The body needs time to adapt and to start using fats as energy instead of carbs.
It is suggested that a multivitamin or fibre supplement can help ameliorate this imbalance. Also it is necessary to consume a good amount of electrolytes and healthy fats during this period.
Since this diet is high in fats, it is said to alter cholesterol levels and cause heart diseases. There is not much scientific evidence to prove the same. In fact research proves the reverse- LC diets are safe and bring about an improvement in metabolic parameters.
Other safety concern is that since it leads to loss of water weight and minerals like sodium. Losing water weight shouldn’t be a problem, but loss of minerals could be of concern. Research proves that low carbohydrates do not have adverse effects on kidney.
Low carb diets seem to be a wise option when you are aiming for a healthy and immediate weight loss. It is the best answer to the weight gain caused by low fat diets.
However there are a few things to keep in mind. When starting with an LC diet reduce your carbohydrate intake gradually to avoid the carb flu.
Also once desired weight goal has been achieved eat a healthy proportion of carbohydrates that suit your BMI so that your energy requirements are met. Also make use of the other health benefits that LC diets have in store for you.