Nutrients that give energy – carbs, protein, and fat – and water are needed in different amounts based upon age, physical activity, growth, life stage (e.g., pregnancy), and other factors.
Here is the latest research on how much protein you need, what increases cholesterol, why you need fiber, hydration, and more.
Carbohydrates
Protein
Fats (lipids)
Water
Carbs
What are carbs? Carbohydrates are sugars, starches, and fibers.
Most starches break down to sugars in the body; some are not absorbed by the body and may be considered dietary fiber. Glucose (a sugar) is the body’s preferred energy source. Carbohydrates provide 4 calories of energy per gram.
Carbohydrates providing glucose to the body are primarily found in grains and cereals, dairy, starchy plants (like potatoes and corn), and fruits.
How much carbs do you need each day?
Eating 45 – 65% of your total calories as carbs have been found in studies to correspond to a healthy diet.
For example, if you need 2000 calories a day, 900 to 1,300 calories can be from carbohydrates (225 to 325 grams).
Added Sugar
Added sugars are not found naturally in foods and are added during food manufacturing. It is advised to limit foods with ADDED sugars to less than 10% of your total calories because these foods tend to lack other nutrients and are often high in calories.
Fiber
Fibers are not absorbed into the body but provide roughage/ bulk for a healthy intestine, may form gels that may trap fat and cholesterol, or provide gut bacteria with carbs (in turn may provide some energy to gut cells; e.g., butyrate).
Fiber can slow down digestion by slowing stomach emptying. This may reduce the rate of sugar absorption into the body as well as increase the feeling of fullness.
How much fiber do you need each day? All age groups need approximately 14 grams of fiber per 1000 calories of food.
High fiber foods:
- Veggies
- Whole grains
- Whole fruits, especially pears, dried prunes, apples with skin
- Legumes, especially lentils, peas, beans, soybeans
- Nuts and seeds
Soluble vs. Insoluble Fiber
Fibers are often classified as soluble or insoluble, depending on if they can dissolve in water.
Foods with high amounts of soluble fiber:
- Oats
- Barley
- Beans
- Sweet potatoes
Foods with high amounts of insoluble fibers:
- Whole wheat and other whole grains
- Many vegetables
Prebiotic fibers may stimulate the growth or activity of beneficial gut bacteria and are found in some plants, including onions, garlic, banana, chicory root and Jerusalem artichokes.
Protein
Proteins are used in the body for most structures (e.g., muscle, skin), as building blocks for communication molecules (e.g., hormones), for immune support (e.g., antibodies), gene regulation, in thousands of reactions (enzymes), as transporters, and more.
Proteins are made up of individual units called amino acids.
In order to make a protein, the body needs all of the correct amino acids, in the right amount, available at the same time. If one is missing, it will break down other proteins to get it. Thus, it is beneficial to eat a wide variety of protein foods.
Essential amino acids
The body can make most amino acids on its own except for the essential amino acids:
- Histidine
- Isoleucine
- Leucine
- Methionine
- Phenylalanine
- Threonine
- Tryptophan
- Valine
Conditionally essential amino acids:
Some amino acids become conditionally essential under certain conditions, such as during illness or wound healing, since the needs can outpace the body’s ability to supply them. They include:
- Arginine
- Glutamine
- Cysteine
- Glycine
- Proline
- Tyrosine
How much protein do you need each day?
Protein needs can be estimated as a proportion of total calories or by weight in kilograms (kg; divide pounds by 2.2) and age or life stage.
| Group | Amount per day |
| 0 – 12 months | 1.2 – 1.52 g/kg per day, depending on age |
| 1 – 3 years | 5 – 20% of total calories or ~1 gram per kg |
| 4 – 18 years | 10 to 30% of total calories or 0.85 – 0.95 g per kg, depending on age |
| 19+ years | 10 – 35% of total calories or 0.8 gram per kg |
| Pregnancy | ~1.1 gram per kg |
| Breastfeeding | ~1.3 gram per kg |
Note: During illnesses or wound healing, protein needs increase.
How much is too much protein?
Protein usage by the cells produces nitrogen wastes that can become toxic. The liver and kidneys work continuously to convert these wastes to urine to be removed from the body. Kidney damage may impair this process.
Although no upper limit value has been established, very high protein intake may be associated with bone loss, kidney stones, and kidney damage.
High-dose supplements (not foods) of several amino acids have the potential to cause negative effects.
For example, branch chain amino acids (Iso, Leu, Val) compete with other amino acids such as tryptophan and tyrosine for transport across the blood-brain barrier. Since tryptophan is a precursor to serotonin, there is a risk for decreased neurotransmitter production with high-dose supplements.
Fats (aka lipids)
How fats work:
Fats are found in cell membranes and transporter molecules. They are stored energy, provide shock absorption, and assist in thermal regulation. Fats also assist in the absorption of some vitamins, are needed for some hormones, and much more.
Fat is necessary in the diet. Fats provide 9 calories per gram.
How much fat do you need in your diet each day?
| Group | Amount |
| 1 – 3 years | 30 – 40% of total calories |
| 4 – 18 years | 25 – 35% of total calories |
| 19+ years | 20 – 35% |
Fats are categorized based upon their physical structure: saturated, unsaturated, and trans fat.
Saturated fat
- Fats that are saturated tend to be solid at room temperature. They mostly occur in animal products and in coconut and palm oils.
- Diets should NOT contain more than 10% of your total calories as saturated fat.
- In high amounts, saturated fats are associated with negative health effects, including heart disease, because they can raise LDL (“bad”) cholesterol.
Unsaturated fat
- Unsaturated fats tend to be liquid at room temperature and are found mostly in plant-based foods.
- Monounsaturated fats are found in foods like olive oil, and polyunsaturated fats in canola and soybean oils.
- Unsaturated fats are associated with positive health outcomes when consumed as part of a healthy diet and are often referred to as “good” fats.
Essential fats (omega-3 and omega-6)
- The body is unable to make the unsaturated omega-3 and omega-6 fats, so we must eat them.
- Essential “good” fats include EPA and DHA, as well as others.
- Essential fats have many functions, including supporting cell membranes and cell communication. For example, omega-3 fats promote antioxidant-like effects during an immune response.
Trans fats
- Trans fats occur naturally in a few animal products (butter) but typically are added during the manufacturing process to help preserve foods.
- Trans fats can have negative health effects, and thus very little should be consumed, if at all.
Cholesterol
The body makes cholesterol, uses it for cell membranes, and makes other things from it, such as sex hormones, bile, and vitamin D.
We also consume cholesterol when eating animal-sourced products. Plants do not contain cholesterol.
The liver makes much more cholesterol each day than we eat. The body regulates how much cholesterol is in circulating in healthy persons (and without genetic hypercholesterolemia). Thus, eating cholesterol-containing foods typically does not increase blood “cholesterol” in healthy persons.
Cholesterol is naturally part of LDL and HDL blood transporter particles. LDL sends fats to cells, and HDL transports them back to the liver.
High saturated fat intake from food can raise LDL cholesterol since this blood particle is responsible for carrying the majority of this type of fat. High LDL increases the risk of cardiovascular disease, while higher HDL lowers the risk.
Notes:
- It is advisable to replace foods containing solid fats and hydrogenated oils (butter, lard, shortening, and products that contain these like cookies) with more plant-based fats (canola, olive, soybean oils, avocados, nuts, and seeds).
- Coconut contains higher saturated fat than butter and has been shown to raise LDL cholesterol.
- Trans fats are in hydrogenated and partially hydrogenated oils. Check labels to limit/avoid these fats.
Water
How does water work in the body?
- Provides fluid to transport substances (oxygen, food, wastes)
- Assists in temperature regulation
- Dissolves substances, including electrolytes such as potassium, sodium, that carry an electric charge, which allow muscles to contract and nerves to transmit signals
- Increases cell turgor (firmness of cells)
- Lubricates and cushions cells and joints
How much water do you need each day?
| Group | Total Fluid Needs (from all foods and beverages) | Water and Beverages Needs (approximate) |
| 1-3 years | 6 cups | 4 cups |
| 4-8 years | 7 cups | 5 cups |
| 9-13 years | 9 cups females 10 cupsmales | 7 cups females 8 cupsmales |
| 14-18 years | 10 cups females 14 cupsmales | 8 cups females 11 cupsmales |
| Adults | 12 cups females 16 cups males | 9 cups females 13 cups males |
| Pregnancy | 13 cups | 10 cups |
| Breastfeeding | 16 cups | 13 cups |
Notes:
- Fruits, many veggies, and foods like soups contain high amounts of water and contribute to your daily fluid needs.
- Fluid needs increase during exercise, with increased altitude, wound healing, persistent diarrhea or vomiting, fever, burns, exposure to heat or cold, certain medications (e.g., diuretics), and during pregnancy and breastfeeding.
- Proper hydration of skin is important for supporting skin structure and which may reduce the appearance of wrinkles.
Sources.
Content was curated using information from:
- The National Academy of Medicine’s Dietary Reference Intake manuals dated 2005 and newer
- The Dietary Guidelines for Americans 2015-2020
- The Office of Dietary Supplements Health Professional’s webpages (accessed Mar-April 2020)
- The Oregon State University’s Linus Pauling Institute’s Micronutrient Information Center (accessed Mar-Apr 2020)
- The USDA’s SR28 food database and FoodData Central database
- From peer-reviewed journal articles
Content presented here, although created by US Registered Dietitians and PhD-level Nutritional Biologists, is for informational purposes only and is not intended to be medical advice. Consult your health care provider before using any supplements or making dietary changes.