One of the fundamental rules of nutrition is “calories in, calories out”. This means you have to avoid consuming too many calories (calories in) and make sure to burn some calories through physical activity (calories out). The goal is to have a balance where you’re not consuming way more calories than you are spending. If you consume lots of calories and don’t spend those calories through physical activity, those calories get stored as fat in your body. When too many calories are stored as fat instead of being used, you start to gain weight and get increased pressure on your heart and blood vessels. This can lead to heart disease and other problems down the road. The “calories in, calories out” rule means there are two things you can do to maintain your physical health:  

1. limit the calories you take in;  
2. increase the calories that you spend by engaging in physical activity. 

Today’s article focuses on the first approach by looking at a way to help people limit the number of calories they take in. A recent study¹ examines whether showing calories on food menus helps people stay healthy.   

This study was done in England, UK and was published earlier this year. It was done in response to the passing of a law in England that required large restaurants and food stores to list the calories of each item on their menus. The thinking behind the law is that showing people calories in different dishes will help them choose lower calorie meals; a strategy that has been shown work ². However, it may be years before all of the health benefits of this calorie labeling law are seen. The researchers behind this study wanted to get a preview of how this law could affect health in the population over the long-term. They aimed to predict whether labeling calories at food businesses could lead to less deaths from heart disease in the next 20 years.  

The researchers made detailed computer simulations to predict how many deaths from heart disease could be prevented by labeling calories on menus. They started by gathering data on a large number of population health trends in England. These included data on the prevalence of heart disease, trends in population demographics, food consumption, dieting behaviors, Body Mass Index (BMI), and mortality rates. The researchers then used this data, and data from past research, to train the computer simulations. The researchers used their programs to predict how many deaths would be expected in a simulation where food businesses labeled the calories of their dishes. They then compared the counts to a simulation where there was no calorie labeling to see the difference labeling would make.  

The researchers looked at the results in two ways: 1) what the next 20 years might look with the current calorie labeling practices, and 2) what the next 20 years would look like if all food businesses labelled their calories. The results showed that labelling calories at large food-businesses in England could prevent 730 deaths from heart disease over the next 20 years. However, if all food businesses in England (large or small) labelled their calories, it could prevent 9200 deaths from heart disease. These results suggest that helping people track their calories and make healthier food choices can save lives in the larger population.  

Calorie – Calories are units of energy. Specifically, a calorie is the amount of energy it takes to raise the temperature of 1 gram of water by 1 degree Celsius. People usually talk about calories when describing the energy that people get from eating food. Scientists are able to estimate how much energy food will produce when eaten in terms of calories. 

Prevalence – Prevalence describes how common something is in a population. For example, if most of your family members have smartphones, you would say that smartphones are very prevalent in your family. Meanwhile, if your hardly anyone has smartphones in your friend’s family, you would say smartphones are not very prevalent in their family.  

Population Demographics - Population demographics are features of the people in a population (such as the population of a country or city). Common population demographics include the age of the people in a population and the number of males and females. 

Body Mass Index (BMI) - is a measure of the size of a person’s body that is used to determine whether they are at a healthy weight or if they are overweight. BMI is calculated from peoples’ height and weight.  

Mortality Rate – the rate of death in a population over a certain period time (usually a year).  

Computer Simulation - A computer simulation is a computer program that acts out events in a way that is similar to how those events would happen in real life. For example, scientists can create a computer simulation of a car crash so they can see what might happen when you crash a car without having to crash a car in real life. 

1. Colombet Z, Robinson E, Kypridemos C, Jones A, O’Flaherty M. Effect of calorie labelling in the out-of-home food sector on adult obesity prevalence, cardiovascular mortality, and social inequalities in England: a modelling study. The Lancet Public Health. 2024;9(3):e178-e185. doi:10.1016/S2468-2667(23)00326-2 
2. Robinson E, Boyland E, Christiansen P, et al. Is the effect of menu energy labelling on consumer behaviour equitable? A pooled analysis of twelve randomized control experiments. Appetite. 2023;182:106451. doi:10.1016/j.appet.2023.106451