The science of satiety per calorie

Evidence based

At Diet Doctor, we want to help everyone understand the concept of satiety per calorie and how it can contribute to healthy weight loss. 

The question is simple: Which foods are the most filling and satisfying per calorie? If you know that, you can focus on those foods in order to control hunger, which can help with weight loss.

But even though the concept is simple, you may benefit from a deeper understanding of why some foods are better for satiety. 

In this educational guide, we’ll review the nutrition science behind a satiety-per-calorie approach. Then, once you are up to date on the science, you can read our practical guides to learn how to put higher-satiety eating into practice.


What is satiety?

Satiety essentially means the feeling of being full or no longer hungry. It doesn’t mean feeling overfull or stuffed. Instead, it might help to think of it as the absence of wanting more food (e.g., not feeling hungry).

Preventing or minimizing hunger could be one of the most important aspects of a sustainable, healthy weight loss routine.


Why satiety per calorie?

It can be easy to avoid hunger for a while by eating a huge meal. But huge meals come with plenty of calories. And too many calories can sabotage your goal of losing weight and improving your health. 

That’s why we want to introduce the idea of satiety per calorie

Eating foods that offer higher satiety per calorie allows you to feel fuller with fewer calories. That way, you can control hunger while eating the right number of calories for you.

Why do we think that a focus on satiety per calorie can help you create a sustainable calorie deficit and lose weight? Because you’ll prioritize foods that provide you with all the protein and nutrition you need while beating back hunger.

Plus, we think you’ll find higher-satiety foods you can love. That combination is a recipe for a healthy, sustainable way of eating.


The science of satiety

Multiple factors can affect how you feel satiety, hunger, or fullness. Based on nutrition science and clinical experience, we believe there are four well-established qualities that make a food more satisfying:

  • protein percentage 
  • energy density
  • fiber content
  • a low hedonic factor

Different factors, such as carbohydrate content, glycemic index, micronutrient content, speed of eating, and others may also contribute to satiety. However, we believe these factors are directly or indirectly captured by the four main variables listed above and therefore do not likely further impact a food’s satiety per calorie.

Let’s look at each component individually.

Protein percentage

Research consistently shows that higher protein diets are more satiating than lower protein diets and that people eating more protein tend to eat fewer calories.

There’s a theory called “protein leverage” that suggests humans and many species of animals keep eating until they get enough protein. You can listen to our podcast with the originators of the theory, Professors Raubenheimer and Simpson from Australia, for more details. 

In brief, research performed on a variety of animals, including humans, suggests that our bodies instinctively search for a certain amount of protein. While the exact amount is difficult to determine, it is likely in the range of 20 to 30% of total calories for most people. However, population data suggest that most Americans are averaging only 16% protein, with many falling well below this level.

The protein leverage hypothesis states that by eating a diet with more high protein foods, we naturally reduce our overall caloric intake, thereby aiding healthy weight loss.


In addition, protein-containing whole foods tend to provide nearly all the micronutrients your body needs. This is key since any micronutrient deficiency could contribute to negative health consequences or possibly a desire to eat more.

Increasing the protein you eat can further help with satiety by increasing satiety hormones such as cholecystokinin and peptide YY (CCK and PYY). These hormones signal to your brain that you have eaten enough and no longer crave or need to search for food.

And since protein has a higher thermic effect (meaning the calories you burn while digesting a food) than carbs or fat, eating more protein can further help maintain a negative energy balance.

To learn more about the benefits of higher protein diets, we have detailed guides focusing on protein percentages and high protein foods.


Energy density

Energy density refers to how many calories a food has per gram or ounce. Foods with high energy density have lots of calories packed into a small amount of food, while foods with low energy density offer fewer calories in that same amount of food.

For example, spinach has a low energy density. One would have to consume an unrealistically large volume of spinach to overeat calories. Instead, when you eat lots of spinach, you’ll fill up your stomach and get some needed nutrients without digesting many calories. 

Potato chips, donuts, and oils have a very high energy density. You don’t have to consume many grams or ounces of these foods to get a lot of calories.

Not surprisingly, multiple studies report that lower-energy-density diets correlate with improved satiety and weight loss compared to higher-energy-density diets.

Lower-energy-density foods also tend to be higher in fiber and water, and lower in starch, sugar, and fat. This may account for some, but not all, of the satiating effect.


Fiber content

The data on fiber are more variable, but overall, fiber appears to have a beneficial effect on short-term satiety.

It’s well accepted that the fiber in fruits and vegetables helps give bulk to food, even as it is digested. This extra bulk in your digestive tract could contribute to feelings of fullness and signals to stop eating. 

However, as mentioned previously, low-energy-density foods tend to also be higher fiber foods. It is hard to tease out the effects of fiber independent of its presence in low-energy-density foods. That may be why not all studies find independent benefit from fiber supplements.

Regardless, it appears that when higher fiber levels occur naturally in foods, they contribute to short-term satiety.


Hedonic factor

The final major contributor to satiety is a food’s hedonic factors.

Scientific data show that certain foods have addiction-like properties, stimulating someone to eat more, despite the absence of traditional hunger. Both the level of processing and combined fat and carb content contribute to the hedonic factor.

A classic example of this would be a snack food, like potato chips, that you can’t stop eating, even after you are no longer hungry.

For many people, carbs or fat by themselves — a plain baked potato or a spoonful of canola oil — may not be tempting. But the combination of them, paired together in a potato chip, is not only tempting, but hard to stop eating. 

In addition, adding sugar to any food or drink may make it more stimulating for the brain and thereby increase cravings for more.  

By choosing foods with low levels of hedonic factors, you may be better able to control your cravings and reduce your propensity to overeat unneeded calories.


What about carbs and glycemic index?

Carbohydrate content and the glycemic index/load of individual foods did not make our list of the top four satiety factors.

That isn’t because we feel carbs and glycemic factors are not important. Not at all. In fact, some studies report higher carb foods cause more brain reward stimulation, potentially leading to overeating. 

We believe the satiety-lowering qualities of high-glycemic foods and refined or simple carbs are already accounted for in our model. This is because they tend to have lower protein content, higher energy density, lower fiber content, and higher hedonic factors.


Other factors

There may be other factors that affect feelings of fullness or satiety, but it is unclear if they independently impact satiety similar to the four main factors listed above. 

For instance, solid and higher-viscosity foods appear to be more satiating than liquids and lower-viscosity foods. Also, more food variety can lead to increased caloric intake and reduced feeling of fullness. Even how fast you eat may influence feelings of satiety.

However, the research into these other factors doesn’t show a strong, consistent impact on satiety, above and beyond the evidence-based impact of protein percentage, energy density, fiber content, and hedonic factors.


What are the highest satiety-per-calorie foods?

Since satiety increases with higher protein percentage, it should be no surprise that some of the highest satiety-per-calorie foods are seafood, meat, chicken, eggs, soy, and low fat dairy. And, since satiety increases with lower energy density, fibrous vegetables are also top options.

To learn more about high-satiety-per-calorie foods, please see our guide: Higher-satiety eating: the best foods

Putting it into practice

Now that you understand the science behind satiety per calorie, it’s time to put your knowledge into practice. You can start with our recipes which now list the satiety score in the nutrition information section. You can also try our high protein meal plans and read more in our other guides on higher-satiety eating.

  1. Are you curious about our use of the term “satiety”? It’s a bit of a compromise. 

    From an academic standpoint, “appetite” is the term that includes the two concepts of “satiation” and “satiety.” Satiation refers to the acute sensation of not wanting to eat anymore at the end of a meal. Satiety refers to the absence of hunger during the time before you want to eat your next meal. However, for simplicity, we use satiety as a blended term that encompasses all feelings of fullness and not wanting to eat.

  2. The following study shows micronutrients track well with protein content, suggesting higher protein meals provide higher nutrition.

    Frontiers in Nutrition 2019: Higher protein density diets are associated with greater diet quality and micronutrient intake in healthy young adults [nutritional epidemiology study with HR less than 2, very weak evidence]

    And the following studies report reduced caloric intake with higher protein meals:

    PLoS One 2011: Testing protein leverage in lean humans: a randomized controlled experimental study [randomized trial; moderate evidence]

    American Journal of Clinical Nutrition 2005: A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations [randomized trial; moderate evidence]

  3. Trends in Food Science and Technology 2015: Optimising foods for satiety [overview article; ungraded]

    European Journal of Clinical Nutrition 1995: A satiety index of common foods [overview article; ungraded]

  4. Obesity Reviews 2014: Protein leverage and energy intake [systematic review of randomized trials; strong evidence]

    American Journal of Clinical Nutrition 2005: A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations [randomized trial; moderate evidence]

  5. American Journal of Clinical Nutrition 2013: Protein leverage affects energy intake of high-protein diets in humans [randomized trial; moderate evidence]

    PLoS One 2011: Testing protein leverage in lean humans: a randomised controlled experimental study [randomized trial; moderate evidence]

  6. JAMA Network 2019: Trends in dietary carbohydrate, protein, and fat intake and diet quality among US adults, 1999-2016 [cross-sectional observational study; very weak evidence]

  7. Frontiers in Nutrition 2019: Higher protein density diets are associated with greater diet quality and micronutrient intake in healthy young adults [cross-sectional observational study; weak evidence]

  8. Nutrients 2017: Risk of deficiency in multiple concurrent micronutrients in children and adults in the United States [cross-sectional observational study; weak evidence]

  9. Journal of Obesity and Metabolic Syndrome 2020: Clinical evidence and mechanisms of high-protein diet-induced weight loss [overview article; ungraded]

  10. Nutrition and Metabolism 2004: Diet induced thermogenesis.[overview article; ungraded]

    Nutrition and Metabolism 2014: A high-protein diet for reducing body fat: Mechanisms and possible caveats. [overview article; ungraded]

  11. Obesity 2014: Assessment of satiety depends on the energy density and portion size of the test meal [randomized trial; moderate evidence]

    American Journal of Clinical Nutrition 2007: Dietary energy density in the treatment of obesity: a year-long trial comparing 2 weight-loss diets [randomized trial; moderate evidence]

    American Journal of Clinical Nutrition 2001: Energy density of foods affects energy intake across multiple levels of fat content in lean and obese women [randomized trial; moderate evidence]

    Physiology & Behavior 2009: The relationship between dietary energy density and energy intake [overview article; ungraded]

  12. Journal of Nutrition and Metabolism 2019: The role of fiber in energy balance [overview article; ungraded]

  13. One review on fiber concluded that with fixed energy intake, an increase in either soluble or insoluble fiber increases post-meal satiety and decreases hunger. And with ad-lib caloric intake, higher fiber correlates with overall lower energy intake.

    Nutrition Reviews 2001: Dietary fiber and weight regulation [overview article; ungraded]

    But a systematic review of studies that examined different fiber sources found inconsistent results, and only a minority of included studies reported improved satiety. The authors postulated many potential reasons why their results weren’t as favorable toward fiber as earlier review articles, but we can’t offer a definitive explanation.

    Journal of The American College of Nutrition 2013: The effect of fiber on satiety and food intake: a systematic review [systematic review of randomized trials; strong evidence]

  14. Cell Metabolism 2019: Ultra-processed diets cause excess calorie intake and weight gain: An inpatient randomized controlled trial of ad libitum food intake [randomized trial; moderate evidence]

    Cell Metabolism 2018: Supra-additive effects of combining fat and carbohydrate on food reward [non-controlled study; weak evidence]

  15. PLoS One 2015: Which foods may be addictive? The roles of processing, fat content, and glycemic load [non-controlled study; weak evidence]

  16. American Journal of Clinical Nutrition 2013: Effects of dietary glycemic index on brain regions related to reward and craving in men [randomized trial; moderate evidence]

    Journal of Nutrition 2021: Diets varying in carbohydrate content differentially alter brain activity in homeostatic and reward regions in adults [randomized trial; moderate evidence]

  17. Scientific Reports 2020: Food texture influences on satiety: systematic review and meta-analysis [meta-analysis of randomized and nonrandomized trials; moderate evidence]

  18. American Journal of Clinical Nutrition 2021: Effect of food variety on intake of a meal: a systematic review and meta-analysis [meta-analysis of randomized and nonrandomized trials; moderate evidence]

  19. Clinical Nutrition 2014: The effect of eating rate on satiety in healthy and overweight people — A pilot study [randomized trial; moderate evidence]