A number of people follow a low-carb diet to lose weight, with an increasing number of studies supporting its effect on weight loss. The amount of carbs consumed each day depends on each individual and their personal health goals.
While you do not need to follow a low-carb diet, it is often recommended that you at least restrict your intake of carbs when trying to lose weight.
Why follow a low-carb diet?
Carbohydrates stimulate the secretion of insulin, which is the main fat storage hormone. Not only can this hamper your body’s ability to burn fat for energy, it may result in an increased appetite and lead to overeating.
By reducing the amount of carbs you eat in each meal or snack, you can generally maintain fairly a low insulin level throughout the day, rather than causing it to spike after eating. This should help your body to burn fat for fuel and prevent hunger, so you end up eating less each day. Those following a low-carb diet generally eat more protein and fat to compensate, and these macronutrients are often much more satiating than carbs.
This actually goes against most advice recommended by health authorities over the last few decades, which often recommended a low-fat diet, with a focus on calorie restriction. While this sounds perfectly fine in theory, when put into practice it tends not to work; even when people stick to the diet diligently they often struggle to get results and frequently feel hungry.
However, more and more research is backing a low-carb diet as an effective way to eat fewer calories without having to actually focus too much on counting calories and creating a calorie deficit.  
Diets that restrict carbohydrate intake have wider health benefits as well, as they tend to lower blood sugar and triglycerides. 
How many carbs do I need?
As yet, there is no specific definition of carbohydrate intake needed for a diet to be low-carb, and each person’s ideal intake will vary depending on age, activity levels and gender.
Physically active people with a higher muscle mass will be able to consumer more carbs than people who do not exercise, particularly if this increased activity comes in the form of high-intensity exercise.
Another large factor in recommended carb intake is an individual’s metabolic health, as the rules are slightly different for those with type 2 diabetes or metabolic syndrome. This is because these people usually aren’t able to tolerate the same level of carbs, with this sometimes referred to as ‘carbohydrate intolerance.’
It is best to talk to your doctor before beginning a low-carb diet, especially if you have a medical condition or take medication.
Ketogenic, moderate and liberal low-carb diets
As a basic starting point, removing the unhealthiest sources of carbohydrates, such as added sugars and refined products, will help you to improve your health. In order to take this on further and feel all the benefits of a low-carb diet then other carb sources will also need to be limited.
Although there are no definitive scientific papers to explain the exact levels of carbs needed for each person, the following are some general guidelines that tend to be helpful.
Liberal: 100-150g of carbs per day
Reducing your carb intake to this level would represent a fairly liberal low-carb diet. It tends to be most appropriate for people who are already lean and active, whose focus is on staying healthy and maintaining their weight.
You can lose weight with this level of carb intake, but it may be necessary for you to control portion sizes and count calories in order to do so.
Carbs you can eat:
- Lots of different vegetables – those grown above ground contain fewer carbs
- Several pieces of fruit per day (fruit can be high in sugar so do not go overboard)
- Restricted amounts of healthy starches such as potatoes, sweet potatoes and healthier grains like rice and oats
Moderate: 50-100g of carbs a day
The more moderate amount of 50-100g of carbs a day is perfect for effortless weight loss, while still allowing for small amount of carbs.
It’s considered a particularly good range for carb-sensitive people who are looking to maintain their current weight.
Carbs you can eat:
- Plenty of vegetables – those grown above ground contain fewer carbs
- Maybe 2-3 pieces of fruit per day (berries contain fewer carbs)
- Minimal amounts of starchy carbohydrates
Ketogenic: 20-50g of carbs per day
This is the most drastic form of low-carb diets, but is also the most effective for losing weight.
While eating at this level of carb intake, your body is likely to go into ketosis, a stage where your body will produce ketones (which can be used throughout the body as fuel), with your body finding it easier to burn fat for energy rather than glucose.
At this point, you’re likely to have a very small appetite and will lose weight much more quickly.
However, because this is a very strict low-carb diet, it is not suitable for everyone, so again please discuss it with your doctor beforehand.
Carbs you can eat:
- Plenty of low-carb vegetables (those grown above ground)
- Some berries
- Trace carbs from other foods like avocados, nuts and seeds
Because every person is different, you may need to experiment to find the level of carb intake that works best for you, because you may find a strict low-carb diet to be too extreme to adhere to properly.
What kind of foods should I be eating?
Weight loss isn’t the only reason for utilising a low-carb diet, as it improves your health overall. It helps encourage you to cut out added sugars and heavily processed food such as pastries and junk food, which can increase your risk of developing certain health conditions.
As a result, your diet should be based on real, whole foods. Added sugar and refined wheat products should be avoided generally, as these are likely to lead to weight gain.
Fat burning properties of low-carb
As well as bringing glucose into cells (and so causing fat to be stored in the body), insulin tells the kidneys to retain as much sodium as possible, so a high-carb diet can cause huge amounts of water retention; when carbs are cut, the lack of insulin causes your kidneys to remove excess water. 
People frequently lose a large amount of weight from water in the first week of eating a low-carb diet. After that, weight loss tends to slow down, but it does at least come from the loss of fat.
Low-carb diets are especially good at reducing levels of belly fat, which has been linked to numerous diseases. 
It is very common that people who are new to eating low-carb will go through an adaptation period in which you are likely to feel fatigued, and may even get headaches. This is usually referred to as the ‘low-carb flu’ and will last for a few days, until your body is used to its new method of producing energy. The effects of this can be greatly reduced by adding more fat and sodium to your diet.