Understanding What are the Worst Calories for Your Health

October 1, 2025 •

4 min read

According to the World Health Organization, limiting intake of certain fats and sugars is critical to preventing noncommunicable diseases. Understanding what are the worst calories means looking beyond the raw number and focusing on a food's nutritional value and impact on your body.

Quick Summary

This article explains the difference between empty and nutrient-dense calories, highlighting added sugars, trans fats, and refined carbs as the most detrimental. It details their negative health impacts and provides actionable steps to avoid them.

Key Points

Empty vs. Nutrient-Dense: A calorie is a unit of energy, but its source matters greatly; empty calories provide minimal nutritional value, unlike nutrient-dense ones.
Added Sugar is a Major Culprit: A primary source of empty calories, added sugars contribute to weight gain and increase the risk of cardiovascular disease.
Trans Fats are Highly Detrimental: Industrially produced trans fats harm heart health by raising bad cholesterol and lowering good cholesterol levels.
Refined Carbs Cause Blood Sugar Spikes: Stripped of fiber and nutrients, refined carbohydrates cause rapid blood sugar fluctuations, contributing to weight gain and disease risk.
Focus on Whole Foods: Prioritizing whole foods like fruits, vegetables, and whole grains naturally helps you avoid the worst calories and boosts your nutrient intake.

A calorie is a unit of energy, but simply counting calories doesn't provide a complete picture of a food's health impact. The crucial distinction lies in the concept of 'empty' versus 'nutrient-dense' calories. Empty calories are those derived from foods with high energy content but little to no nutritional value, including vitamins, minerals, protein, or fiber. Nutrient-dense calories, on the other hand, fuel the body with essential components that support optimal function and health. Focusing on the source of your calories is key to maintaining a healthy diet and preventing chronic disease.

The Prime Suspects: What are the worst calories?

Certain food components are consistently identified as providing the most detrimental calories. These are often found in highly processed items and offer quick energy spikes followed by crashes, leading to poor health outcomes over time.

Added Sugars

Added sugars, also known as free sugars, are a major source of empty calories and are a primary target for dietary reduction. They are found in an enormous range of products, from sugar-sweetened beverages and candy to packaged snacks and flavored yogurts.

Health Impacts: High intake of added sugars can lead to unhealthy weight gain, increased risk of dental caries, and contribute to risk factors for cardiovascular diseases. It can also cause blood sugar spikes and crashes, which are linked to cravings and overeating. The American Heart Association recommends limiting added sugar to no more than 25-36 grams per day, depending on gender.
Common Sources: Soda, sports drinks, fruit juices with added sugar, candy, desserts, and sweetened breakfast cereals.

Trans Fats

Industrially produced trans fats are perhaps the most dangerous type of calorie. The World Health Organization attributes more than 278,000 global deaths annually to trans fat intake. The body has no need for these fats, and their consumption significantly increases health risks.

Health Impacts: Trans fats raise harmful LDL ('bad') cholesterol while simultaneously lowering beneficial HDL ('good') cholesterol. This double-trouble effect increases the risk of heart attacks and stroke. They are also linked to inflammation and insulin resistance.
Common Sources: Fried fast foods, baked goods (like cookies and crackers) made with partially hydrogenated oils, some margarines, and processed snacks.

Refined Carbohydrates

Refined carbs are whole grains that have been processed to remove the bran and germ, which contain fiber and nutrients. This leaves behind a starchy endosperm that is quickly broken down into glucose.

Health Impacts: They cause rapid spikes in blood sugar and insulin levels, which can lead to insulin resistance and an increased risk of type 2 diabetes and heart disease. The quick digestion and lack of fiber can also lead to overeating and weight gain.
Common Sources: White bread, white rice, pasta, pastries, sugary cereals, and bagels.

The Consequences of Empty Calories

Consuming a diet high in empty calories has far-reaching consequences beyond simple weight gain. These effects can accumulate over time, increasing the risk of numerous chronic illnesses.

Weight Gain and Obesity: The high energy density and low satiety of empty calorie foods make it easy to consume more calories than needed, leading to weight gain.
Increased Inflammation: Trans fats and added sugars have been linked to increased inflammation throughout the body, a key contributor to many chronic diseases.
Increased Risk of Chronic Disease: High intake of refined carbs, trans fats, and added sugars is strongly linked to type 2 diabetes, heart disease, stroke, and certain cancers.
Nutrient Deficiencies: By displacing nutrient-dense foods, empty calories can lead to a diet lacking essential vitamins, minerals, and fiber.

Making Better Choices

The good news is that avoiding the worst calories often involves simple food swaps. Prioritizing whole, unprocessed foods naturally reduces your intake of added sugars, unhealthy fats, and refined carbs.

Here are some simple swaps to make your diet more nutrient-dense:

Beverages: Choose water, unsweetened tea, or coffee instead of soda, fruit juices, or energy drinks.
Snacks: Opt for fresh fruit, nuts, or seeds instead of candy, cookies, or potato chips.
Grains: Swap white bread and pasta for whole-wheat bread, brown rice, or quinoa.
Fats: Use healthy unsaturated fats from olive oil, avocados, and nuts instead of trans fats and excessive saturated fats.

Comparison of Empty vs. Nutrient-Dense Calories


Feature	Empty Calories (Worst)	Nutrient-Dense Calories (Best)
Nutritional Value	Low or none (minimal vitamins, minerals, fiber)	High (abundant vitamins, minerals, fiber, protein)
Energy Release	Rapid spikes and crashes in blood sugar	Slower, sustained energy release
Satiety	Low; often leaves you feeling hungry soon after	High; promotes a feeling of fullness for longer
Health Impact	Associated with chronic diseases, inflammation, weight gain	Supports overall health, weight management, and disease prevention
Examples	Soda, candy, fast food, refined carbs	Fruits, vegetables, whole grains, lean protein, nuts, legumes

Conclusion: Prioritizing Nutrition over Energy

All calories are not created equal. While a calorie is a measure of energy, a food's impact on your health is determined by its nutritional density. The worst calories are those that come from added sugars, trans fats, and refined carbohydrates. These empty calories can increase inflammation, promote weight gain, and elevate the risk of chronic diseases. By focusing on a diet rich in fruits, vegetables, whole grains, and lean proteins, you can swap out these detrimental calories for nutrient-dense ones that will nourish your body and support long-term health. Making these conscious choices is a powerful step towards a healthier, more vibrant life.

How to make dietary changes for long-term success

Making sustainable dietary changes involves more than just a fleeting change; it's about adopting long-term habits. Begin by reading nutrition labels carefully to identify hidden sugars and trans fats. Replace one sugary drink a day with water or unsweetened tea. Gradually introduce more whole grains, fruits, and vegetables into your meals. Plan your meals to reduce the temptation of fast food. Remember that small, consistent changes are often more effective than drastic, temporary restrictions. For more detailed guidance, consider consulting an evidence-based resource like the Dietary Guidelines for Americans.

Frequently Asked Questions

The terms are often used interchangeably. 'Empty calories' refers to the technical concept of calories that offer energy without nutrients. 'Bad calories' is a more casual term for these same energy-rich, nutrient-poor calories, as their consumption is linked to negative health outcomes.

No. While a gram of fat contains more calories than a gram of protein or carbs, healthy unsaturated fats (like those in avocados and olive oil) are vital for nutrient absorption and satiety. The truly 'bad' fats are industrially produced trans fats and excessive saturated fats from processed sources.

Check nutrition labels for 'added sugars' and the ingredient list for 'partially hydrogenated oils' to avoid trans fats. Also, choose whole grains over 'enriched' or 'refined' grains, which have been stripped of fiber and nutrients.

While consistently consuming more calories than you burn will lead to weight gain, bad calories contribute more significantly because they are often less filling and easier to over-consume. They also tend to be stored as fat more readily and can lead to inflammation.

Fruit juices often contain high amounts of free sugars and, unlike whole fruits, lack the fiber that slows sugar absorption. This makes them a source of empty calories and a less healthy choice than eating whole fruit.

While the goal is to limit them, a balanced approach allows for occasional indulgences. The key is moderation. The majority of your diet should consist of nutrient-dense, whole foods to support your health and prevent the negative effects of empty calories.

Yes, chronic high intake of bad calories, particularly trans fats and added sugars, has been linked to increased inflammation in the body. This inflammation is a risk factor for many chronic conditions, including heart disease and diabetes.