The most energy rich nutrient is

Macronutrients, which are essential components of foods we eat, provide calories. Carbohydrates, protein, and fats are the three types of macronutrients, and foods and beverages contain varying amounts of these nutrients. The energy-density of food refers to the number of calories in a certain quantity. Fat is the most energy-dense macronutrient found in foods.

Calories in Macronutrients

Paying attention to the energy-density of foods is important since consuming large amounts of high-calorie foods contributes to weight gain and obesity. Gram for gram, each macronutrient contains a certain number of calories. Carbohydrates and protein each contain 4 calories per gram, while fat contains 9 calories per gram. Since fat contains more than double the number of calories per gram of carbs or protein, it is the most energy-dense.

Types of Fats

Not all fats are created equally, as some are healthier than others. Fats are found naturally in foods such as olive oil, nuts, cheese or beef, or they are sometimes added to foods. Types of fats include unsaturated, saturated and trans. Monounsaturated and polyunsaturated fatty acids are the two types of unsaturated fats and are considered the most beneficial for health when consumed in moderation. Unsaturated fats are primarily found in plant-based oils, nuts, and fish. Saturated fat, which should be limited in the diet, is found in tropical oils and high-fat dairy and meats. Trans fat is usually a man-made type of fat added to packaged snack foods or baked goods, and is the least healthiest type. All types of fats contain 9 calories per gram.

Health Implications

Overweight or obese individuals are at higher risk of developing heart disease, type 2 diabetes and certain types of cancer. Choosing foods that have lower energy density allows us to consume a greater amount of food for fewer calories, thus limiting excess weight gain. For example, one tablespoon of butter and 2 cups of sliced strawberries both have approximately 100 calories, which means the strawberries are lower in energy density. According to the Mayo Clinic, consuming more foods that have low energy density helps us feel full and keeps weight off for the long term.

Macronutrient Recommendations

All three macronutrients are essential and important for our health and thus should be consumed in varying amounts. The Institute of Medicine has established estimated recommendations for macronutrient intake, based on total calories consumed per day. Adults should aim to obtain approximately 45 to 65 percent of their daily calories from carbohydrates, 10 to 35 percent from protein, and 20 to 35 percent from fat. The Nutrition Facts label found on most foods is useful for understanding the amounts of each macronutrient in a product.

Technically, a calorie is defined as the amount of heat necessary to raise the temperature of one gram of water by one degree centigrade. But in layperson's terms, the calorie is a unit of how much energy your food gives you – and if you eat more energy than your body uses, your body stores the excess as fat. So it's just a bit ironic that of the three macronutrients (fat, protein and carbohydrate), it's fat that gives the most energy – or calories – per gram.

Fat: 9 Calories per Gram

Fat provides the most energy of all the macronutrients, at a whopping 9 calories per gram. That's why even a small amount of food or condiments that are rich in fat can pack so many calories. For example, a single tablespoon of creamy peanut butter has a whopping 191 calories, more than 75 percent of which come from its 16.44 grams of fat. Carbohydrates and protein each pack just 4 calories per gram, less than half the energy in a gram of fat.

The Role of Fats

Each macronutrient has its place in a healthy diet, and the fact that fat contains more calories than carbohydrates and protein doesn't make it inherently bad. In fact, Dietary Guidelines for Americans 2015-2020 recommends that 25 to 35 percent of the calories in your diet should be made up of fats. The trick is to make sure you consume healthy unsaturated fats, like those you get in nuts, avocados and fish. Less than 10 percent of your daily calories should come from saturated fats, which you'll find in many meats and fast food. As much as possible, limit or exclude trans fat, which makes foods shelf-stable but has a serious impact on your health.

The Role of Carbohydrates

Carbohydrates are the first and quickest form of energy that your body turns to when it needs fuel. Because of this, simple or fast-acting carbohydrates from foods like candy, baked goods and juices can cause a spike and then a crash in blood sugar and energy levels. Complex carbohydrates, which include whole grains and legumes, raise your blood sugar levels more slowly, give you more sustained energy and even help you feel full longer. According to the Dietary Guidelines for Americans, 45 to 65 percent of your daily calories should come from carbohydrates.

Adding Protein

Your body can burn protein as energy, but it's also used for growth and maintenance. Think of it as a set of building blocks that your body can use for renovations. Protein takes a long time to digest, and it elevates your blood sugar levels very little, so while it's not your body's preferred quick-acting fuel, high-protein snacks like jerky and soy nuts won't cause you to peak and crash, either. According to Dietary Guidelines for Americans, 10 to 35 percent of your daily calories should come from protein.