Understanding calories, weight loss, and type 2 diabetes

Many believe calories to be the scourge of a healthy lifestyle. So we’re here to let you know the truth about calories, why they’re so important, and how you should think about them if you have type 2 diabetes.
Simon Lovick
min read
Checked by

Quick summary

  • A breakdown of what calories are, and why they’re important to understand for a balanced diet
  • Why you should avoid the ‘calories in calories out’ mentality
  • Advice for healthy sources of calories, and foods to avoid if you have type 2 diabetes
  • What is caloric restriction—and why it may or may not be useful for helping your diagnosis

Ever wondered what that little number is on restaurant menus or the side of food packaging? 

If you’ve ever been on a diet plan or a weight loss regime, you’ll recognise the obsession around the C word—calories. Calories are the unit of energy that each food contains, and are a way of measuring the fuel that humans need to consume in order to keep going through the day. 

One easy trap to fall into, though, is thinking that calories are bad. We think of calorific foods as unhealthy and indulgent, counter to a clean lifestyle. If you’ve received a type 2 diabetes diagnosis, you may have a hyper-awareness around calorie intake. Well, we’re here to debunk that myth and provide you with everything you need to know about calories, what their benefits are, and how you should approach them if you have type 2 diabetes. 

What are calories?

To understand calories, you need a basic understanding of how the human body works. You need to regularly top up a car with petrol to keep it running; similarly, you need to regularly top up your body with energy to keep it functioning. Everything we eat and drink contains (to varying degrees) a source of energy that powers our everyday bodily functions, from exercising and breathing, to digesting and thinking—this energy comes in the form of calories. 

On any food packaging, you’ll be able to see the calorific content on the information on the back. This is usually marked by ‘kcal’, or kilocalories. 

What is the recommended daily intake of calories? Well, this varies a lot depending on age, size, and how much exercise you’re doing—but on average, men need 2500 kcal a day and women need 2000 kcal.[1] 

For a balanced diet, you should try to make sure that your calorie intake is roughly equal to your energy output. This is what is referred to by many as ‘calorie in calorie out’, or CICO. This is used by many as a guideline around the recommended calorie intake and how you can lose weight. This is not, however, an exact science (as we’ll explore later in this article). 

Are calories bad?

Given the fear-mongering around “high-calorie foods”, you wouldn’t be unreasonable to think that calories are bad for you. Eating a very high calorie diet will result in your putting on weight: for people with a type 2 diabetes diagnosis, this certainly isn’t advisable. But by and large, in answer to that question: no, calories are not bad. Calories are literally the fuel for your body, so you couldn’t function without them. 

The reason for this, which is worth underlining, is that not all calories are equal. Different sources of calories are treated by your body in different ways, having both positive and negative effects. That’s why the CICO rule is not something to hold fast to.

Carbohydrates, and the calories your body extracts from them, are a great example of how different foods have a different impact. Different types of food contain either simple or complex carbohydrates. This essentially means they are made up of simple (short, easy to break down) or complex (long, hard to break down) structures of sugar. 

Not all calories are equal

Wholegrains (pasta, rice, etc), pulses, unrefined grains (quinoa, bulgur wheat, oatmeal), and root vegetables (like sweet potatoes, sweetcorn, and squash) are a good example of complex carbohydrates. It takes your body longer to break these down to absorb glucose into the bloodstream, meaning you have a slower release of energy, and feel energised and sustained for a longer period of time.[2]

Foods with processed sugars (sweets, fizzy drinks, fast food), however, are simple carbohydrates. Because their structures are quicker to break down, sugar is absorbed far more quickly resulting in a blood sugar spike. Many people will be familiar with this ‘sugar buzz’: those living with type 2 diabetes will know how this results in a sharp increase in insulin in the body causing your blood sugar to rapidly fall.[3] Long term effects of this can be harmful too. Leptin is the hormone that makes you feel full: having elevated insulin levels will lead to leptin resistance, meaning you’ll never feel satisfied after a meal and you’re likely to overeat. 

Should people with type 2 eat carbs? Definitely. In fact, if you have a type 2 diabetes diagnosis, it’s recommended that you get around 50% of your calories from carbohydrates.

Wegovy is here! Start your free assessment

Complete the assessment and purchase your plan

Mounjaro is here! Start your free assessment

Complete the assessment and purchase your plan

Caloric restriction 

One method for treating type 2 diabetes is through caloric restriction: literally, reducing the number of calories you put into your body. This is most commonly performed by implementing a low-carb diet. Depending on their weight, people with type 2 diabetes may usually be recommended to consume around 1800 kcal a day. 

There are a number of known benefits of caloric restriction. For one, caloric restriction can help with weight loss (a very important step for tackling type 2 diabetes). Simple carbs, as we outlined earlier, lead to unstable blood glucose levels, and the resulting excess glucose is stored by the body as fat. Leptin resistance too will lead you to feel hungry even after a large meal. Reducing your carbohydrate intake will help tackle this; or, at the very least, replacing it with more complex carbs will help.[4]

A low-carb diet and reduced calorie intake helped 25% of study participants reach remission without the need for medication

Saslow et al., JMIR Diabetes

A low-carb diet will also help to manage your blood sugar levels. Restricting calorie intake will reduce your likelihood of blood glucose spikes, mimicking the impact of medication like insulin. This is a great preventative method for those with type 2 diabetes. What’s even more exciting is that, in some cases (25% in a 2018 study), adopting a low carb diet and decreasing your calorie intake can actually lead to type 2 diabetes reversal.[5]

It’s not a simple miracle cure, though. Caloric restriction comes with certain challenges. For one, keeping up a strict, restrictive diet can be tough: it can cause high degrees of stress, which has a big impact on your mental and physical health, and can often cause you to lapse back into bad habits.[6]

In the short term, it can pay dividends through weight loss, blood sugar stability, and even remission: but studies have found that after 12 months, many of these benefits diminish. [7] This may be because it’s hard to sustain diets. In short, evidence of the long term benefits of caloric restriction is not conclusive.  

Advice around dieting with type 2 diabetes

What you eat is one of the most important factors around your risk of developing type 2 diabetes, or for treating it post-diagnosis. We know that unhealthy diets and obesity are significant risk factors

You should certainly be mindful of what and how much you eat. Different diet plans will work for each individual, so it’s worth seeking advice on what the right plan is for you. If you are embarking on a diet, try and maintain a positive relationship with food: be creative with what you cook, try not to view dieting as a chore, and reward yourself with the occasional treat. Journaling can also be a good companion to implementing healthy eating habits. 

There’s no point fearing calories. Instead, your focus should be on being more thoughtful about what you’re putting in your body and understanding the impact that different foods have on your type 2 diabetes. The long term benefits of this, physically and mentally, will be vast. 


[1] What should my daily intake of calories be? NHS. Retrieved 31 March 2022. Accessible here.

[2] Complex carbohydrates. MedlinePlus, US National Library of Medicine [updated 20 August 2020). . Retrieved 31 March 2022. Accessible here

[3] Here's everything you need to know about fruit sugar. Aaptiv. Retrieved 31 March 2022. Accessible here.

[4] Musa-Veloso, K., Poon, T., Harkness, L.S., et al. (2018). The effects of whole-grain compared with refined wheat, rice, and rye on the postprandial blood glucose response: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr 108(4):759-774. Accessible here.

[5] Saslow, L.R., Summers, C., Aikens, J.E., Unwin, D.J. (2018). Outcomes of a digitally delivered low-carbohydrate type 2 diabetes self-management program: 1-year results of a single-arm longitudinal study. JMIR Diabetes 3(3):e12. Accessible here.

[6] What happens to your brain when you go on a diet? NBC News. Retrieved 31 March 2022. Accessible here.

[7] Goldenberg, J.Z, Day, A., Brinkworth, G.D.. et al. (2021). Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: systematic review and meta-analysis of published and unpublished randomized trial data. BMJ 372:m4743. Accessible here.

Related articles