Every field has its jargon, and the ketogenic diet and low-carb nutrition is worse than most. This glossary covers the 36 terms that come up again and again in our guides and in the questions readers send us. Definitions are short on purpose: enough to unblock you, with links to deeper guides throughout the site when you want the full story.

Adaptation Period

The phase when your body adjusts to using fat for fuel instead of carbohydrates, typically lasting 1-4 weeks. During this time, you might experience fatigue or headaches before feeling better.

Appetite Suppression

A common effect where eating high-fat, high-protein foods reduces hunger and makes you feel fuller longer. This natural decrease in appetite often helps people eat fewer calories without trying.

Basal Metabolic Rate (BMR)

The number of calories your body burns at rest just to maintain basic functions like breathing and circulation. It varies based on age, sex, weight, and muscle mass.

Beta-Hydroxybutyrate

One of the main ketone bodies produced when your body breaks down fat for energy. It’s used by your brain and muscles as fuel when glucose is scarce.

Caloric Deficit

When you consume fewer calories than your body burns, which is necessary for weight loss. Weight loss requires a deficit whether you’re following keto or any other diet.

Carbohydrate Cycling

A strategy where you eat very low carbs on some days and slightly higher carbs on others, often timed around workouts. This approach may help some people maintain muscle while staying mostly in ketosis.

Carb Creep

The gradual addition of small amounts of carbohydrates that can creep back into your diet over time. Even small increases can potentially slow or stop ketosis progress.

Cheat Day

A planned day where you eat foods outside your normal low-carb or keto plan. A single cheat day can take several days to recover from metabolically.

Cyclical Ketogenic Diet

A version of keto where you eat very low carb most days but have one or two days per week with higher carbohydrate intake. It’s often used by athletes who need extra carbs for intense training.

Dirty Keto

Following ketogenic macros but using processed foods high in additives instead of whole foods. While it may keep you in ketosis, it often lacks micronutrients and may cause digestive issues.

Electrolytes

Minerals like sodium, potassium, and magnesium that help your body maintain fluid balance and muscle function. Low-carb diets can deplete electrolytes, sometimes causing muscle cramps or fatigue.

Fat Adaptation

The metabolic shift where your body becomes efficient at burning fat and ketones for fuel instead of glucose. This typically takes 4-8 weeks and improves energy levels and mental clarity.

Fat Bomb

A small, calorie-dense snack made primarily from fat, often with cream cheese, butter, or coconut oil. These are used to increase fat intake or satisfy cravings on keto.

Gluconeogenesis

The process where your body creates glucose from non-carbohydrate sources like amino acids and glycerol. This happens naturally even on keto, but doesn’t prevent ketosis.

Glucose

A simple sugar and the primary fuel source your body normally uses for energy. On keto, you minimize glucose intake to force your body to use fat instead.

Glycemic Index (GI)

A measure of how quickly a food raises blood sugar levels, with lower numbers indicating slower, steadier increases. Low-GI foods are generally better for blood sugar control.

Insulin Resistance

A condition where your cells don’t respond properly to insulin, leading to higher blood sugar and insulin levels. Low-carb diets may help improve insulin sensitivity over time.

Intermittent Fasting

Eating all your food within a specific time window and fasting for the rest of the day, such as eating only between noon and 8 PM. Many people find it pairs naturally with keto since fat keeps you full longer.

Keto Flu

A collection of temporary symptoms like headaches, fatigue, and irritability that some people experience when starting keto. It usually resolves within a few days to a week as your body adapts.

Ketone Bodies

Molecules produced by your liver when fat is broken down for energy, serving as fuel for your brain and body. The three main ketones are acetoacetate, beta-hydroxybutyrate, and acetone.

Ketosis

A metabolic state where your body burns fat for fuel and produces ketones instead of relying on glucose. This is the main goal of the ketogenic diet.

Lipid Panel

A blood test that measures your levels of total cholesterol, LDL, HDL, and triglycerides. Monitoring this can help you understand how diet affects your heart health markers.

Macronutrients

The three main categories of nutrients your body needs in large amounts: carbohydrates, protein, and fat. Keto typically aims for about 70-75% calories from fat, 20-25% from protein, and 5-10% from carbs.

Metabolic Rate

The speed at which your body burns calories at rest and during activity. It’s influenced by age, genetics, muscle mass, and activity level.

Micronutrients

Vitamins and minerals your body needs in small amounts to function properly. Low-carb eating requires attention to certain micronutrients like potassium and magnesium.

Net Carbs

Total carbohydrates minus fiber, representing the carbs that actually affect blood sugar and ketosis. Different sources calculate net carbs differently, so consistency matters more than perfection.

Nutritional Ketosis

A safe metabolic state achieved through diet where ketone levels are elevated enough for health benefits but not dangerously high. It’s different from diabetic ketoacidosis, which is a dangerous medical condition.

Protein Sparing Modified Fast (PSMF)

An extreme low-carb approach where you eat mostly protein with very little fat or carbs for rapid weight loss. It requires medical supervision and should only be done temporarily.

Satiety

The feeling of fullness and satisfaction after eating that makes you less likely to eat again soon. High-fat and high-protein foods tend to increase satiety more than carbohydrates.

Standard Ketogenic Diet (SKD)

The most common version of keto with consistent very low carbs, moderate protein, and high fat every day. It works well for weight loss and general health for most people.

Targeted Ketogenic Diet (TKD)

A keto approach where you eat small amounts of carbs specifically before or after intense exercise. This may help athletes perform better while mostly staying in ketosis.

Thermogenesis

The process of heat production in your body, which requires energy and burns calories. Eating protein increases thermogenesis more than carbs or fat.

Total Carbs

The complete amount of carbohydrates in a food, including both fiber and digestible carbs. This number appears on nutrition labels and is different from net carbs.

Type 2 Diabetes

A condition where your body struggles to regulate blood sugar because cells resist insulin. Low-carb and keto diets may help manage or reverse type 2 diabetes in some people.

Water Retention

The temporary holding of extra water in your body, which can add pounds on the scale without adding fat. Starting keto often causes quick water loss, which is why initial weight drops can be dramatic.

Weight Cycling

The pattern of repeatedly losing and gaining significant amounts of weight, sometimes called yo-yo dieting. Long-term adherence matters more than rapid weight loss for lasting results.