Why is soup so low in calories? Unpacking the science of volume eating

November 7, 2025 •

3 min read

According to research published in the journal PLOS ONE, individuals who ate soup regularly were approximately 40% less likely to be overweight than non-soup eaters. This remarkable statistic highlights a crucial principle of nutrition: why is soup so low in calories? The answer lies not just in its ingredients but in a concept known as volume eating.

Quick Summary

Soup is so low in calories because its high water content and nutrient-dense ingredients like vegetables and lean protein fill you up quickly. This boosts satiety, helping to reduce overall calorie consumption. Broth-based soups are especially effective for weight management by providing significant volume with minimal calories.

Key Points

Low Energy Density: Soups, especially broth-based ones, are low in calories relative to their volume due to their high water content.
High Satiety: The large volume of soup fills the stomach, signaling fullness to the brain and helping to curb overall calorie intake.
Fiber-Rich Ingredients: Adding vegetables and legumes to soup increases its fiber content, which slows digestion and prolongs feelings of fullness.
Lean Protein: Including lean protein sources like chicken, lentils, or tofu boosts satiety, helping to regulate appetite and prevent overeating.
Cooking Method Matters: Broth-based soups are ideal for weight management, while creamy, high-fat versions can significantly increase the calorie count.
Nutrient-Dense: Healthy soups pack a variety of vitamins, minerals, and antioxidants, providing significant nutritional value for a low-calorie investment.
Effective Pre-Meal Strategy: Eating a low-calorie soup before a main meal can reduce the amount of food and calories consumed during that meal.
Homemade vs. Store-Bought: Making your own soup at home allows for better control over ingredients, especially sodium and fat levels, which are often high in commercial options.

The Core Principle: Energy Density and Volume

The main reason soup is so low in calories is its low energy density. Energy density refers to the number of calories in a given amount of food. Because soup consists mostly of water, it offers a large portion size with a relatively small number of calories, especially when compared to solid meals of the same caloric value. This principle, often called volume eating, allows you to fill your stomach and feel satisfied without consuming a lot of energy.

High Water Content for Maximum Satiety

The water content in soup plays a significant role in promoting fullness, or satiety. This is because water adds volume and weight to the food, which signals to the brain that the stomach is full. A study conducted at Pennsylvania State University found that people who ate soup before a main meal consumed about 134 fewer calories overall. The hydration provided by soup is also a crucial benefit, as water is essential for various bodily functions, including metabolism and appetite regulation.

The Power of Fiber-Rich Ingredients

Fiber-rich vegetables and legumes are another key component of low-calorie soups. Fiber adds bulk to the soup without adding many calories. It is also a complex carbohydrate that the body digests slowly, which helps to stabilize blood sugar levels and prolong feelings of fullness. When making homemade soup, packing it with vegetables like cabbage, broccoli, and carrots maximizes the fiber content.

Lean Protein for Lasting Fullness

Incorporating lean protein into soup recipes further enhances its satiating effect. Protein is a macronutrient that promotes feelings of fullness more than carbohydrates or fats. Adding ingredients such as cooked chicken breast, lentils, chickpeas, or tofu can significantly boost the protein content, helping to keep you full for longer and manage appetite. This sustained satisfaction helps prevent overeating later in the day.

Cooking Method Matters

The way a soup is prepared has a massive impact on its final calorie count. Broth-based soups, which rely on low-calorie liquids like vegetable or chicken stock, are the most beneficial for weight management. In contrast, creamy soups thickened with high-fat ingredients such as heavy cream, butter, or cheese can drastically increase the calorie and saturated fat content, undermining the benefits. A study in the European Journal of Clinical Nutrition found that a smooth pureed soup could enhance satiety even more effectively than a chunky version, further supporting the idea that a smooth, thick consistency can boost feelings of fullness.

The Comparison: Broth vs. Cream-Based Soups


Feature	Broth-Based Soup (e.g., Minestrone)	Cream-Based Soup (e.g., Cream of Mushroom)
Energy Density	Low to very low	High to very high
Primary Thickening Agent	Fiber from vegetables, legumes	Heavy cream, butter, flour
Key Ingredients	Vegetables, lean protein, legumes	High-fat dairy, cheese
Satiety Source	Volume, water, fiber, lean protein	Fat and caloric density
Weight Management	Highly effective for reducing overall calorie intake	Less suitable due to high caloric load
Nutrient Profile	Rich in vitamins, minerals, and antioxidants	Can be higher in saturated fats

Conclusion: Strategic Sipping for Success

Understanding why soup is so low in calories helps in making smarter dietary choices. It is a tool for volume eating, allowing you to consume a satisfying amount of food for a minimal number of calories, especially when opting for homemade, broth-based versions loaded with vegetables, fiber, and lean protein. By leveraging the power of satiety and nutrient density, soup can be a delicious and effective ally for anyone focused on weight management. However, it is essential to be mindful of ingredients, as high-fat additions can turn a healthy dish into a calorie-dense one. As a versatile and comforting meal, soup offers a nutritious way to control your calorie intake without sacrificing flavor or fullness.

Frequently Asked Questions

Yes, incorporating low-calorie, broth-based soups into your diet can help with weight loss. Their high water and fiber content promote fullness, which can lead to a natural reduction in your overall calorie intake.

Yes, there is a major difference. Broth-based soups are typically very low in calories, while creamy soups, often made with high-fat ingredients like heavy cream or butter, can be surprisingly high in calories.

To maximize nutritional value and minimize calories, focus on ingredients such as a variety of vegetables (e.g., carrots, broccoli, spinach), lean proteins (e.g., chicken, lentils, chickpeas), and herbs and spices for flavor.

Yes, research indicates that eating a low-calorie soup before a meal can significantly reduce the amount of food and calories you consume during that meal. This is because it helps you feel full faster.

The temperature of the soup does not affect its caloric content. Both hot and cold soups can be beneficial for satiety and weight management, depending on the ingredients.

While convenient, many canned soups are very high in sodium. It's best to check the nutritional label and choose low-sodium options or, even better, prepare homemade soups to control the ingredients.

Yes, you can make soup into a complete meal. Ensure it is balanced with carbohydrates, protein, and healthy fats by adding ingredients like vegetables, beans, lean meats, or whole grains.

Instead of using heavy cream or flour, you can thicken soup with low-calorie, healthy alternatives. Mash some of the cooked vegetables or blend in legumes like lentils or chickpeas.