Low-Carb Diet

An increasing amount of research is showing that a low carb diet is a strong choice for people with diabetes.

Not only have low carbohydrate diets been shown to improve blood glucose levels and aid weight loss but evidence also shows the diet to be strong in terms of heart health.

Low carb diets need not be overly restrictive and can be easily incorporated into your lifestyle without needing to reduce intake of vegetables and fibre. In fact, the reduced focus on carbohydrate intake frequently leads to a stronger vegetable intake.

One of the first, and now, biggest, resources relating to low-carb diets for people with diabetes is the low carb diet forum:

The low-carb diet forum is cited as being popular in highlighting the adoption of a low carbohydrate diet as a way of achieving weight loss and improving HbA1c in patients, despite the approach being generally frowned upon in the UK. [127]

What constitutes a low carb diet?

Disagreement exists as to what should be a healthy minimum level of daily carbohydrate.

Carbohydrates are recognised as one of the fundamental influences on blood sugar levels.

Many people with diabetes find that eating a low-carbohydrate diabetes diet helps them to control blood sugar better than other diet types, including those currently (2015) recommended by the National Health Service.

What counts as low carb?

Charity Diabetes UK provides the following brackets for daily carbohydrate intakes.

A research study in 2008[7] used the following brackets to categorise daily carbohydrate intake:

  • Moderate carbohydrate: 130 to 225g of carbs
  • Low carbohydrate: under 130g of carbs
  • Very low carbohydrate: under 30g of carbs

How do carbohydrates affect the body?

Carbohydrates, as do proteins and fats, provide energy so they help to fuel the body.

Carbohydrates are broken down into glucose so when carbohydrates are consumed, an increase in blood sugar levels occurs to a greater or lesser extent according to the carbohydrate.

By reducing carbohydrate intake, you can help to reduce the rise in blood glucose levels after meals.

How will low-carbing affect my weight?

Low carbohydrate diets have been found to be successful in aiding weight loss.

There is some debate as to how the diet helps.

The reduction in carbohydrates means that people need not produce, or inject, so much insulin. As insulin helps to store fat, less circulating insulin could help to prevent, reduce or reverse weight gain.

A further theory is that by restricting the amount of carbohydrates, people are often restricting their calorie intake to some extent, which also helps it weight loss and weight management.

What is the counter-argument against low-carb diets for people with diabetes?

If low-carb diets can help to reduce blood glucose levels and aid weight loss, then why are low-carbohydrate diets not advocated by the NHS?

The reason that is commonly cited is that there is not enough evidence to support the effectiveness and safety of low-carbohydrate diets.

The question is a hotly debated one which has seen disagreement from both sides as to which diet is more safe and effective.


Low carb diets have been amongst people with diabetes because they are blood sugar friendly. A low carb diet has less carbohydrate than the average diet.

There is no formal definition, but a diet of less than 130g of carbohydrate a day is regarded as low carb. It not uncommon for people with diabetes to have less than 100g of carbohydrate a day.

Low carb diets have become particularly popular with people who have type 2 diabetes. The diet’s also had appeal for people with type 1 diabetes who have either struggled with control on a ‘normal diet’ or who want to tighten their control.

People on insulin, or other blood glucose lowering medication, should take care if reducing their carbohydrate intake as hypoglycemia can occur. We would advise speaking with your doctor first, before making significant changes to your diet.

Some of the benefits of a low carb diet can include:

  • Lower average blood glucose levels - particularly in the period after meals
  • Reduction in ‘brain fog’ that tends to result from higher sugar levels
  • Helping with weight loss

People have also found that low carb diets can improve cholesterol and triglyceride levels.

To reduce your carb intake you will likely cut down on or cut out food such as bread, pasta, rice, potatoes and of course sweeter foods.

Vegetables should be the foundation of a low carb diet –as they should for any diet. You may need to up your intake of protein or fat to compensate for the reduction in carbohydrate. If increasing the amount of fat, ensure you’re getting a good supply of unsaturated fats which are found in nuts, avocados and oily fish.

With any significant change in diet, you may experience a few effects in the first 2 weeks as the body gets use to the change.

This can include:

  • Tiredness
  • Headaches
  • Constipation or loose stools

If these effects don’t subside after a couple of weeks, you may need to make some changes. You may wish to consult a dietitian for advice.

A low carb diet is sometimes viewed as a restrictive diet.

However, many people on the diet find inventive ways to replace starchy foods - such as using swede or celeriac instead of potato, and using cauliflower instead of rice and making dough out of almond meal. You may well find that a low carb diet is more nutritious than your previous diet.

What side effects exist when on a low carb diet?

Low blood sugar (hypoglycemia)

If you significantly reduce your carbohydrate intake, your medication and/or dosage may need to be reviewed to prevent low blood glucose levels –particularly if you take insulin.

Symptoms of low blood glucose levels can include headaches, fatigue and lack of concentration.

It is worth noting that headaches, fatigue and lack of concentration are also symptoms of high blood glucose levels, so the ideal situation is to balance the amount of medication with the carbohydrate intake.

Nutrition deficiency

As with any diet, depending on how it put together, there is the chance that the diet may lack certain nutrients. The inclusion of a variety of fresh vegetables, and certain fruit, can help to offset deficiencies.


Depending on which foods make up the diet, constipation can occur. Inclusion of fibrous vegetables can help to offset the problem.

What should a low carbohydrate diet consist of?

If you are significantly reducing the amount of carbohydrate in your diet, you may need to make up some of the reduced calories with either protein or fat. It is advisable to ensure the fat content includes so called good fats such as:

  • Mono-unsaturated fats: nuts, avocados and olive oil.
  • Polyunsaturated fats: found in fish oils (don’t confuse fish oils with fish served in vegetable oil)

Is a low carb diet not suitable for certain people?

People with reduced kidney function, in particular, are advised to speak with their healthcare team before increasing the amount of protein in their diet.

People with a history of heart trouble may need to be careful about which fats they consume and may be advised to speak with a dietitian.

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