Nutrition Terms

A reference guide to the key terms and concepts behind what you eat and how it affects your body. Whether you're trying to lose weight, build muscle, eat more healthfully, or simply understand food labels, these definitions will help you cut through the noise and make better-informed dietary choices.

• Added Sugar Added sugar refers to sugars and syrups that are added to foods during processing or preparation — as opposed to naturally occurring sugars in fruit and dairy — and is linked to obesity, type 2 diabetes, heart disease, and dental decay when consumed in excess.
• Antioxidants Antioxidants are compounds — found abundantly in fruits, vegetables, and other whole foods — that neutralize free radicals, protecting cells from oxidative stress and reducing the risk of chronic diseases including cancer and heart disease.
• Calories A calorie is a unit of energy — in nutrition, it measures the amount of energy that food provides to your body, and the balance between calories consumed and calories burned is the fundamental driver of weight change.
• Carbohydrates Carbohydrates are one of the three macronutrients — the body's primary fuel source, found in grains, fruits, vegetables, and dairy — ranging from simple sugars to complex starches and dietary fiber.
• Clean Eating Clean eating is a dietary philosophy centered on consuming whole, minimally processed foods while avoiding artificial ingredients, preservatives, and heavily processed products — more a flexible eating framework than a rigid diet.
• Collagen Supplements Collagen supplements are protein-based products — typically powders or capsules — derived from animal connective tissue that provide collagen peptides thought to support skin elasticity, joint health, bone density, and connective tissue repair.
• Dietary Fat Dietary fat is one of the three macronutrients — providing 9 calories per gram, essential for hormone production, vitamin absorption, and cell function — with significant health differences between unsaturated, saturated, and trans fat types.
• Electrolytes Electrolytes are minerals that carry an electric charge in bodily fluids — including sodium, potassium, magnesium, and calcium — essential for hydration, nerve signaling, muscle contraction, and maintaining fluid balance.
• Fiber Dietary fiber is a type of carbohydrate that the body cannot digest — found in plant foods, it supports digestive health, blood sugar regulation, cholesterol reduction, and satiety, yet most Americans consume far less than recommended.
• Glycemic Index The glycemic index (GI) is a scale from 0 to 100 that ranks carbohydrate-containing foods by how quickly they raise blood glucose levels compared to pure glucose — helping people understand a food's impact on blood sugar.
• How to Read a Nutrition Label Reading a nutrition label means understanding the Nutrition Facts panel, serving sizes, ingredient lists, and daily value percentages to make informed food choices — a foundational skill for anyone monitoring their diet.
• Hydration Hydration is the process of maintaining adequate fluid levels in the body — water is essential for nearly every biological function, and even mild dehydration measurably impairs physical performance, cognitive function, and overall health.
• Keto Diet The ketogenic (keto) diet is a very low-carbohydrate, high-fat eating approach that shifts the body into a metabolic state called ketosis, where fat becomes the primary fuel source instead of glucose from carbohydrates.
• Macronutrients Macronutrients are the three primary categories of nutrients the body requires in large amounts for energy and function — protein, carbohydrates, and fat — each serving distinct physiological roles.
• Meal Prep Meal prep is the practice of planning and preparing food in advance — typically in a dedicated weekly session — to save time, control portion sizes, reduce food waste, and support consistent healthy eating throughout the week.
• Metabolism Metabolism is the collection of all chemical processes that convert food into energy and support life — including the rate at which the body burns calories — influenced by age, body composition, genetics, and lifestyle factors.
• Micronutrients Micronutrients are vitamins and minerals that the body needs in small amounts to support essential physiological functions — from energy metabolism and immunity to bone health and blood clotting.
• Nutrient Density Nutrient density is the ratio of beneficial nutrients — vitamins, minerals, protein, fiber — to the total calories a food provides, making it a useful measure of how much nutritional value you get per calorie consumed.
• Omega-3 Fatty Acids Omega-3 fatty acids are essential polyunsaturated fats — found in fatty fish, flaxseed, and walnuts — that support heart health, brain function, and inflammation reduction, and cannot be produced by the body in sufficient quantities.
• Plant-Based Diet A plant-based diet is an eating pattern that emphasizes foods derived from plants — vegetables, fruits, legumes, whole grains, nuts, and seeds — while minimizing or eliminating animal products, and is associated with reduced risk of heart disease, type 2 diabetes, and certain cancers.
• Portion Control Portion control is the practice of eating measured, deliberate amounts of food — distinguishing between a standard serving size and the amount you actually consume — to manage calorie intake and support healthy eating goals.
• Probiotics Probiotics are live microorganisms — beneficial bacteria and yeasts — that when consumed in adequate amounts confer health benefits by supporting a balanced gut microbiome, improved digestion, and immune function.
• Protein Protein is a macronutrient made of amino acids that serves as the primary building block for muscle, tissue, enzymes, and hormones — essential for growth, repair, immune function, and maintaining body composition.
• Saturated Fat Saturated fat is a type of dietary fat — solid at room temperature, found in red meat, dairy, and tropical oils — traditionally linked to elevated LDL cholesterol and heart disease risk, though the science is more nuanced than early guidelines suggested.
• Sodium Sodium is an essential mineral and electrolyte that regulates fluid balance, nerve transmission, and blood pressure — but most Americans consume far more than recommended, contributing to hypertension and cardiovascular disease risk.
• Vitamins Vitamins are essential organic compounds required in small amounts for normal growth, metabolic function, and disease prevention — categorized as either fat-soluble (A, D, E, K) or water-soluble (C and the eight B vitamins).
• Whole Grains Whole grains are grain foods that contain all three parts of the grain kernel — the bran, germ, and endosperm — retaining more fiber, vitamins, and minerals than refined grains, which have had the bran and germ stripped away.