A calorie is a unit of measurement. It’s designed to show you how much energy a given food provides.
Every cell in your body requires energy, so calories are essential for your health. But a calorie count won’t tell you how a meal affects your health.
In this article, you’ll discover what factors influence your personal calorie needs — and why food labels don’t really tell you how many calories you’re taking in.
At ZOE, we believe that the quality of the calories you eat is more important than the number of calories.
With ZOE's personalized nutrition program, you can learn how to eat for your health and long-term weight goals.
Daily calorie needs
The Dietary Guidelines for Americans recommend that women eat around 1,600–2,400 calories a day, while men should aim for about 2,000–3,000 calories.
But these are general guidelines. Your actual calorie needs depend on:
your body size
your activity levels
your overall health goals
whether you’re taking medications
whether you’re pregnant or breastfeeding
Energy needs vary considerably from person to person. For example, not all 50-year-old women need the same number of calories, not all men need more than women, and calorie needs aren’t the same for every pregnant mother.
Calories on food labels
Counting calories may seem straightforward: Tally up the numbers on the nutrition labels of everything you consume in a day and compare the total with your recommended calorie intake.
But there’s a hitch.
The numbers of calories on food labels often aren’t accurate. And how many calories your body takes in from a particular food may differ from what’s on the label.
The figures on labels are estimates of how much energy a given serving of food provides, based on the calories in each ingredient.
But the serving sizes on labels are often much smaller than what people typically eat. This can make it challenging to accurately count calories, unless you’re meticulously weighing all your food.
And, again — the label doesn’t necessarily tell you how much energy your body can get from the food.
Also, the quality of calories from different types of food can mean different things for your health.
Two hundred calories from a bottle of soda will affect you very differently, compared with 200 calories from avocado spread on whole grain toast.
In a recent episode of the ZOE Science & Nutrition podcast, Dr. Sarah Berry — ZOE’s chief scientist and a reader in nutritional science at King’s College London — said, “In my opinion, the back of pack labeling or the nutrition composition and the calories only tell us one piece of a thousand-piece puzzle.”
The idea behind calorie counting is: If you take in more energy, or calories, than you use up, your weight will increase.
The problem is that you don’t just take in calories, you eat food. And foods are complex. Their structure (the food matrix), how you prepare them, and how you combine them can all affect how your body responds.
What are your energy needs?
General guidelines give you a broad range of calories to aim for. But ultimately, the number of calories you need every day is unique to you.
A number of factors can influence your daily needs, and a nutrition expert, such as a registered dietitian, can help identify what’s right for you.
ZOE’s PREDICT program — the largest nutritional research program of its kind — shows that everyone has different responses to foods.
You can take our free quiz to find out how ZOE’s personalized nutrition program can help you eat for your body and long-term goals.
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Quality over quantity
If you want to improve your overall health, it's better to focus on the quality of your calories rather than their number.
Some healthy foods have more calories. For example, foods rich in healthy fats, like avocados, vegetable oils, and nuts, provide lots of energy — and they can benefit your health in a number of ways.
A great way to improve your diet is to include a variety of minimally processed, nutrient-dense plant foods, including:
vegetables, such as spinach, carrots, broccoli, cauliflower, and kale
fruits, such as apples, pears, oranges, avocado, raspberries, and peaches
whole grains, such as quinoa, barley, oats, buckwheat, and bulgur wheat
legumes, such as chickpeas, kidney beans, black beans, peas, and lentils
nuts and seeds, such as almonds, pecans, sunflower seeds, and hemp seeds
spices and herbs, such as turmeric, oregano, basil, and rosemary
healthy oils, such as extra virgin olive oil
And as part of your focus on quality, try to limit foods with little nutritional value, like ultra-processed foods. Some examples include:
soda and other sweetened drinks
baked treats, like cookies, cakes, and buttery breads
packaged chips, crackers, and other snacks
candy and energy bars
Risks of calorie counting
Calories play a role in health and weight management, but continually counting them may not be the best approach. For example:
It’s unsustainable. It takes time and work to count all your calories, and it can be hard to stick with in the long term.
It’s probably not accurate. As we mention above, the numbers you see on labels may not really reflect how many calories you’re taking in, even if you measure servings perfectly every time.
Plus, estimating calories gets even more complicated when you’re dining out or eating things like pasta, casserole, or soup.
It can lead to an unhealthy relationship to food. Counting calories can be all-consuming, which can interfere with a healthy relationship to food.
It ignores important nutrients. Calories measure energy, which is only one part of a very complex puzzle. Foods also provide you with vital nutrients, and the calorie count can’t tell you what nutrients are in your food.
Calories are a way to measure the amount of energy a type of food provides.
The Dietary Guidelines for Americans recommend that women eat 1,600–2,400 calories every day, while men should aim for 2,000–3,000 calories.
However, your age, height, activity levels, and several other factors influence your calorie needs. How your body responds to food also plays a role.
Also, a calorie count can’t show whether food is good for you. It’s important to be getting enough high-quality calories and plenty of nutrients in your diet.
Simply focusing on calories can carry some risks. It can be tough to sustain, and it can lead you to develop an unhealthy relationship to food. Plus, coming up with accurate calorie estimates can be very difficult.
At ZOE, we believe that one of the best ways to promote your health is to focus on the quality of your food and to choose options that are best for your unique biology.
A healthy, balanced diet will include a diverse range of vegetables, fruits, grains, legumes, nuts, seeds, herbs, and oils.
With the ZOE at-home test, you can learn about your blood sugar and blood fat responses, as well as which “good” and “bad” bugs live in your gut. Based on your unique results, we can give you personalized nutrition advice so you can learn how to eat for your body and long-term goals.
Dietary guidelines for Americans, 2020–2025 and online materials. (2020). https://www.dietaryguidelines.gov/resources/2020-2025-dietary-guidelines-online-materials
Energy balance: Totaling up energy expenditure. (n.d.). https://www.hsph.harvard.edu/obesity-prevention-source/energy-balance/
Foods, obesity, and diabetes — are all calories created equal? Nutrition Reviews. (2017). https://academic.oup.com/nutritionreviews/article/75/suppl_1/19/2797600
Predicting personal metabolic responses to food using multi-omics machine learning in over 1000 twins and singletons from the UK and US: The PREDICT 1 study. Current Developments in Nutrition. (2019). https://academic.oup.com/cdn/article/3/Supplement_1/nzz037.OR31-01-19/5517817?login=false
The carbohydrate-insulin model: A physiological perspective on the obesity pandemic. The American Journal of Clinical Nutrition. (2021). https://academic.oup.com/ajcn/article/114/6/1873/6369073
The truth about fats: The good, the bad, and the in-between. (2022). https://www.health.harvard.edu/staying-healthy/the-truth-about-fats-bad-and-good