As you can imagine, feeling full on fewer calories is a critical strategy for weight loss and weight maintenance. Being able to reduce calorie intake is the most powerful way to lose weight, even better than exercise. If you can successfully reduce calories so you are in an energy deficit, you can lose weight.

Common dieting wisdom is that you have to cut portion sizes to cut calories. However, eating smaller portions usually just makes you hungry and that's not something you can stick with for a long time. The problem of course is the hunger villain. If it gets out of control, you'll lose, every time.

Is there solution to this? Yes, and here's the secret:

Certain foods make you more full and satisfied than others with overall less calorie intake.

For example, if you could feel just as full and satisfied at 1200 calories per day as you would at 1800 calories per day, you've just cut 600 calories per day without any hunger.

With this strategy, you can eat ample portions -- not skimpy portions -- and still lose weight. In many cases, you could eat as much as 3 TIMES the volume for the same calories! Wouldn't it be wise to focus on eating those certain foods, instead of other foods?

This is a diet that you can eat for basically forever to lose weight or maintain weight.

In fact that's one of the most exciting things about high-satiety low calorie density foods is that they just happen to be foods that are good for your body as well. So choosing these foods also creates a healthy eating style that you use for a lifetime. You can do it for maintenance after losing on a rapid weight loss plan... or you can do it as a primary means of losing weight.

Why does this work?

Research shows that feeling full -- and consequently how much we eat over a one or two day period -- is due to food weight and volume, not calories. When we eat food that is bulky or weighs a lot, it stretches our stomach. Our homeostatic eating system senses that stretch, and sends satiety (fullness) signals to the brain. So if you eat a meal high in calories, you can gain weight regardless of whether or not you feel full. If you eat a meal that is low in calories but stretches the stomach or prolongs digestion, our brain gets the "full" signal and you naturally eat less.

This is a surprising strategy because your homeostatic eating system that monitors energy (calorie intake) would normally be expected to complain -- but it doesn't, at least a lot less than you'd think. Neither you (your conscious mind) or your biological hunger hormones seem to notice. It's like you are tricking your body into accepting fewer calories. And the effect doesn't just last for one meal: studies show that just because you consume fewer calories at one meal, if the bulk and weight was enough, you don't necessarily eat more later.

One way or another, highly filling foods either fill you up faster at a meal, or the food remains in your stomach longer. And if those same filling foods happen to be lower in calorie density, then those are very effective foods for weight loss and weight control.

As we said above, it makes a lot of sense to focus on eating those types of foods as much as you can. The more you do, the more weight you lose.

Finding the Best Weight Loss Foods

Research and studies have shown two primary ways of identifying the most filling, lowest calorie foods.

Calorie Density Method: This approach is based on a calorie-per-gram calculation. It considers the ratio of calories per weight of the food (sometimes volume).

Satiety Response Studies: This approach is mostly based on studies that measure participants' satiety response to a variety of foods, without any preconceived theory about which foods might give that response. So there's no specific formula, although people have derived formulas from the studies. The most famous study was done by Australian researcher Dr. Susanna Holt. We'll tell you about it below.

Interestingly, the two approaches mostly overlap and produce the similar results. However, there are surprises -- some food that may not be the lowest calorie density can keep you full for so long that the extra calories don't matter. So it's ideal to combine both tactics.

We'll describe both below...

Calorie Density Method

What are calorie dense foods? Foods that pack a lot of calories into a small package -- that is, high in calories compared to its weight.

All food consists of some combination of protein, carbohydrate, fat and water (and sometimes alcohol).

Here is the calorie content of basic food components:

Fat: 9 calories per gram
Alcohol: 7 calories per gram
Protein: 4 calories per gram
Carbohydrate: 4 calories per gram
Fiber: 2 calories per gram
Water: 0 calories per gram
Air: 0 calories per gram

From those numbers, we can make some logical observations:

Food containing more water, air or fiber content will have a lower CD
Food containing more fat or alcohol will have a higher CD

Thus, to reduce the total amount of calories while keeping the portion size the same, the greatest effect would be to increase water, air and/or fiber and reduce fat and alcohol.

In the real world, this occurs when you do things like add vegetables to a meal, or when you eat watery foods like soup. You can also think in terms of your average daily calorie density. The lower the total daily calorie density, the more food you were able to eat while keeping calories low. You do this by eating more low CD foods like fruits, vegetables, etc, and consciously limiting foods with high fat content (it's not necessary to eliminate fat, just lower it).

Calculating Calorie Density

Here's an example label:

It's actually pretty easy to do. Simply divide the calories by the serving size in grams, to give you calories per gram. So looking at the nutrition facts label above, you'll see Calories is 174 and the Serving Size is 210 g (grams). To get calorie density, divide 174 by 210 (174/210) which gives you 0.8 calories per gram.

Sidenote: Why do we use weight (grams) instead of volume (like cups)? Because weight is a more precise way to measure. For example, it's difficult to consistently measure 1 cup of broccoli compared to weighing it on a scale. Accuracy and easy of measurement also helps nutrition scientists do their research.

Now you have a number you can use to compare to other foods. The lower the number, the lower the CD and the better it is for reducing calories while retaining portion size.

Here are some rough guidelines:

Very-low CD	Low CD	Medium CD	High CD
Less than 0.6 calories per gram	0.6 to 1.5 calories per gram	1.6 to 3.9 calories per gram	4.0 to 9.0 calories per gram

Famous Satiety Study

The first and most famous study on satiety was done in 1995 by Australian researcher Dr. Susanna Holt and her associates at the University of Sydney. They developed what they called the Satiety Index, which ranks different foods on their ability to satisfy hunger. Other studies have been done on the satiety of specific foods or nutrients (like protein and fiber) but unfortunately there seems to be a lack of large scale studies that directly compare a variety of everyday foods. Other tools such as the one at nutritiondata.self.com are based on the Holt study.

Some takeaways from the study:

Foods that take up a lot of space in the stomach are highly satiating -- basically, food with a lot of air, water or fiber.
Slowly digested and absorbed food keeps you fuller longer: essentially, fiber and protein.

Satiety measurements for the study were done over a period of 2 hours. Most foods were highly satiating over the entire time period. (We wish it had been a longer time period, so we'd know how satiating various foods would be for say, 3 - 5 hours, which is often how long we eat between meals.)

The exception was fruit, where fullness ratings dropped off quickly towards the end of the 2nd hour. This isn't a bad thing -- holding off hunger for close to two hours is pretty remarkable for a mostly-water based food. The fiber is what allows the sugars in fruit to be more slowly absorbed than pure sugar. However it shows the limits of fruit alone; for best satiety it either needs to be eaten more frequently or combined with other more slowly digested food.

As Dr. Holt summarizes, "...roughly speaking, the more fiber, protein and water a food contains, the longer it will satisfy ... [for example] a wholesome salad sandwich on wholegrain bread with some lean protein like tuna, or beef and an apple... can keep hunger at bay for a very long time."

Common Characteristics

Combining the Calorie Density Method and the Dr. Holt's satiety study, we can conclude that the best weight loss foods (high satiety, low calorie density) tend to have the following characteristics, in no particular order:

High water content
High protein content
High fiber content
High air content
Low fat content (not always... but most of the time)

Appetite Suppression Effect

When the stomach and small intestines are stretched, it activates a special type of hormone that results in appetite suppression. High volume foods that are "heavy" (high water content), activate this effect. Bulky foods can, too, such as soluble fiber which "gels" and expands in the stomach, or food with a lot of air.

This tends to fill us up sooner at mealtime, so we eat less.

High Water Content

Water is a magic ingredient when it comes to weight loss using the calorie density strategy.

First, water weighs more than any other food component. As explained earlier, we tend to eat the same amount of food every day by food weight. And the weight of food can trigger appetite suppression at mealtime.

Second, the high-water foods have lower calorie density because water has ZERO calories and weighs a lot. Thus, high-water foods always have a lower CD than drier foods. In fact, the highest CD foods are dehydrated food (little to no water content) like dried fruit, crackers and chips. For example: Raisins contain eight times (8X) the number of calories of grapes!

This chart shows you the amount of water in various foods. It's surprising how much water is contained in everyday foods. But the greatest effect comes from water content above 80%.

Food	Water Content (%)	Food	Water Content (%)
Vegetables & Fruits	80 - 95%	Pasta, cooked	60 - 65%
Soups	80 - 95%	Meats	45 - 65%
Hot cereal	80 - 95%	Cheese	35 - 55%
Yogurt, low-fat, fruit	75%	Bread	35 - 40%
Egg, boiled	75%	Nuts	2 - 5%
Fish and seafood	60 - 85%	Crackers & chips	2 - 3%
		Oil	0%

High Protein Content

Protein is a dieter's secret weapon. Studies show it has the highest short-term and long term satiety rating of any other type of nutrient. That means that it helps you get full faster at a meal, and keeps you fuller longer after a meal, as compared to any other nutrient.

You'll find that the higher the protein content of food, the better the food will score in satiety (fullness) rankings.

Take full advantage of that! See Protein.

High Fiber Content

Entire diets have been based on just increasing fiber intake. A lot of medical research supports fiber as a proven way to lose weight and stay healthy. Fiber stimulates the release of certain intestinal hormones, promotes a feeling of satisfaction earlier in the meal, and prolongs sense of fullness by slowing the emptying of the stomach. Fiber allows you to have a "full plate", instead of tiny portions.

In terms of calories, fiber contributes so few calories you don't need to count them; so, it's basically like adding water. It's a great way to lower the CD of food.

As a bonus, natural high-fiber foods function like "nature's broom" by cleaning out your large intestines and keeping you "regular".

High Air Content

As mentioned above, high air content of food can help trigger an appetite suppression effect.

Studies with smoothies show that people get fuller and eat less later if the smoothie has higher air content (done by blending on high for a longer time). Likewise, people eat fewer calories of cheese puffs when they are puffy versions instead of more compact.

Other examples: air-popped popcorn, mousse, rice cakes, puffed cereal, flaked cereal (more volume versus compact cereal like granola).

Low Fat Content

Limiting fat content is a big part of lowering the caloric density because fat is so calorie dense. However, studies (and decades of extreme low-fat dieters) prove that trying to remove all fat from a diet is a bad strategy. That's because our bodies do need some healthy fats, fat helps keep us sustained between meals, and it just makes food less bland. In moderate amounts, it can help you stick to a diet. See Control Fat Intake for more.

How to Pick High Satiety, Low Calorie Foods

Aside from the handy charts, there are some logical conclusions you can make from satiety rankings and characteristics of high-satiety, low-calorie foods.

You can't go wrong consuming lean protein. To achieve maximum long-and-short-term fullness, ideally every snack or meal should contain some amount protein, ideally lean (meaning with low fat content).

As a general rule, foods with water and fiber tend to be low density. That's why you can't go wrong with vegetables and fruits -- They match almost all the characteristics we want for weight loss: they have high fiber, high bulk, low energy density. They aren't the highest in protein, but they do in fact contain a surprising amount of protein, which only adds to the effectiveness. Vegetables tend to have the lowest density of any food. Whole fruit is close by.

Leafy greens are the highest-fiber, lowest-calorie foods you can find. They're so low in calories you could eat immense amounts and still lose weight.

Anything watery is a good bet -- anything from high-water content fruits and veggies, to food like soup, low-calorie drinks... and well, water! (But not fruit juice or non-diet sodas)

If you don't mind the carbohydrate (starch) content, then beans are a real winner, having an extremely high fiber-to-calorie ratio, high protein and good bulk.

A similar guideline: The more chewing resistance a food provides, the less energy dense it is. Chewing resistance typically indicates fiber. But protein (meat) also provides chewing resistance. Chewing resistance is a sign that your stomach will also take longer to digest it, which means you'll get full faster, and stay full longer.

Ultimate simplicity: If you want to make things really simple, just choose whole foods like these:

Protein
Vegetables
Fruits (whole)
Beans

In contrast, you want to minimize food without much water content: crackers, chips, nuts, crackers, dried fruit. Remember the comparison between raisins and grapes.

Strategies for Substitutions & Modifications

A big part of the CD strategy is simply smart substitution, where you swap calorie-dense foods or ingredients you normally eat with less calorie dense versions that taste just as good and/or provide you with a larger portion size.

Even small substitutions and modifications to lower CD of meals can really add up. Everything you do makes a difference!

The most common and most effective tactic for lowering CD is to add more vegetables to any recipe that includes vegetables. You can often add 2 to 5 times as many vegetables and no one will notice -- in other words they are essentially "hidden" and at the same time (true to the CD theory) the amount (volume) of food is greatly multiplied.

A similar tactic is to boost fruit content in desserts and to use fruit to sweeten recipes instead of sugar. More more tips see the Fiber pages: Vegetables, Fruit, Leafy Greens.

Other substitution tactics:

Reduce amount of fat used as toppings, oil in recipes, and in cooking (you can't always taste and appreciate all that fat; a little goes a long way; see Control Fat Intake)
Use higher-fiber whole grain carbs instead of refined carbs like white flour (see Carb Smart Plan).
Use frozen fruit (thawed) for toppings instead of syrup or sugar-infused commercial fruit toppings
Use egg whites or egg white substitute instead of whole eggs (you could include the yolk of one egg for flavor)
Replace some fatty meat with vegetables (example: only use half the amount of hamburger)
Use fat-free half-and-half instead of regular (in recipes, it usually tastes the same)
Use fat-free or low-fat dairy (for milk, yogurt, cottage cheese, cheese, etc)
Use low-fat or fat-free dressings
Make your own dressings that are lower fat
Use skinless, grilled chicken and turkey, instead of fried with skin
Add more liquid to soups
Use lettuce instead of tortillas

Ideal Meal or Snack

Taking it all into consideration, an ideal snack or meal should contain lean protein, a moderate amount of fat, and some fiber (ideally in the form of fruit, vegetable, or green). Grain-based carbs are optional because quite often the other food will have some carbs anyway. But there's no harm in eating high-fiber bread if your body can handle carbs.

See Magic Meals for more.

Avoid The "Fat / Refined Carbohydrate / Salt" Combination

Refined carbs alone are energy dense, but adding fat really boosts the energy density. It's the combination of the two that pack a high-calorie punch.

What exactly are refined carbohydrates? Generally, we mean sugar and flour of various kinds, particularly white flour. Also what we might call "processed potatoes" (potato chips and french fries). See Carb Smart for more.

Probably the most common combination is sweet (sugar plus fat, as in cake, cookies, ice cream, etc). But it also occurs with salty snacks like chips, or french fries.

Are High-Calorie Dense Foods Forbidden?

No, we're not saying you can't ever have high-energy-dense foods. "Forbidden" is a psychologically dangerous word for dieting!

If you are keeping track of the calories, you could eat high energy dense snacks as part of your overall plan, or as occasional indulgences. Or you may decide to eat measured amounts of nuts or dried fruit during a moderate weight loss plan. Regardless, when it comes to weight loss you have to take calorie dense foods seriously. And be very honest with yourself about Trigger Foods. Especially if you are on a strict/short-term rapid weight loss plan.

It's very individual... as everything is. Just make a conscious, educated choice about how energy-dense food fits into your preferences, your health goals, your calories goals.

Three Popular Health Foods To Be Careful Of

Three foods that are eaten as health foods but are energy dense:

Dried fruit
Nuts
Protein bars

Dried Fruit

Dried fruit (raisins, apricots, dates, etc) isn't bad for you -- but it's not a good weight-loss food when you are trying to be strict about calories. The reduced water content makes them more like lumps of sugar with some fiber. Refer to the section above about High Water Content. For example, 2 cups of grapes has 100 calories, but 2 cups of raisins has EIGHT TIMES as many calories (800)!

It's just too easy to consume a lot of calories with dried fruit, and some studies show they tend to actually stimulate hunger. If you do eat dried fruit, do so in moderation (measure out a serving like fats and oil).

Nuts

Nuts are more calorie dense than chocolate. They do have some healthy fats and some protein but, arguably, you can get protein and essential fatty acids in other ways without packing in so many calories. However, studies have shown that eating whole nuts aren't actually absorbed that well in the digestive system, so the net calorie consumption may be only be 5% to 35% or lower depending on the nut! That means the calorie effect isn't as great as you think. Nut butters on the other hand have almost 100% absorption.

Here are some ways you can consume nuts without worry about calorie overload:

Measure out a serving size. Nutrition Facts labels usually have a reasonable portion size.
Limit nut butters (peanut butter, almond butter, etc). Measure controlled quantities like you would do for fats and oils.
Eat nuts with no added salt, and you will naturally eat less.
Buy nuts with shells. If you have to crack and remove the shell, you'll naturally eat nuts in proper amounts (Paleo/hunter-gatherer style!).

Protein Bars

Another food that is considered "healthy" but has questionable value: protein bars.

Protein bars are essentially what we might call "glamorized candy" -- a candy bar with added protein. The sugar content is typically very high and it is very calorie dense. Not a good diet food. If you eat protein bars, save them for workout-related nutrition strategies.

What About Alcohol?

We have detailed information about alcohol on the "Avoid Drinking Calories" page.