Dieting Glossary

This is the final post in the dieting basics series. All the previous posts are linked to from the series outline.

Sometimes, diet books and websites seem full of weird acronyms or scientific terms. Here’s some of the jargon explained, with definitions and links to other posts in the dieting basics series where appropriate.

Where I’ve put a word in bold within a definition, that means the word is explained elsewhere in the list.

Blood sugar

Your “blood sugar level” is the amount of glucose in your blood. It rises when you’ve just eaten, and is lowest first thing in the morning. The body controls the amount of blood sugar in your blood using insulin and your blood sugar levels usually won’t vary very widely during the day.

In everyday terms, “low blood sugar” is often used to describe the weak, drowsy or shaky feelings that people experience if they’ve not eaten for a while.

If you have diabetes, you need to help your body regulate blood sugar levels by taking insulin.


Your Body Mass Index is a number that indicates whether you’re a healthy weight for your height. It’s calculated as your weight in kilograms divided by the square of your height in metres. If that’s too complicated, there’s a handy BMI calculator on the NHS website.

A BMI of 20-25 is considered “normal”. Lower than 18.5 is considered “underweight”, 25-30 is “overweight”, 30-35 is “obese” and 35-40 is “morbidly obese”.


Your Basal Metabolic Rate is a measure of how many calories you burn just to stay alive – which varies according to your weight, height, age and gender. You can work this out using the Basal Metabolic Rate formula. Just knowing your BMR alone doesn’t tell you much: you need to multiply it by a percentage based on how active you are.


The calorie is a unit of energy, and is used both for energy intake (eating food) and energy output (exercising and metabolic functions). The dieting basics guide contains information on what a calorie is, the recommended daily calorie guidelines and how to calculate your personal calorie allowance.

Calorie density or caloric density

The calorie density (sometimes called caloric density or energy density) of a food is a measurement of the average calories per gram of that food. Most food labels indicate the values per 100g of the food, and comparing these across food ranges lets you know which choices will provide more bulk for fewer calories. The higher the calorie density, the more calories there are per 100g.

Foods with higher water contents have lower calorie densities, as water has weight but no calories. There are some great examples of what 200 calories looks like here, showing exactly how much food you get for your calories.

The “Pritikin Principle” or “Pritikin Diet” works by advocating foods with a low calorie density.


Exercise described as “cardio” or “cardiovascular” (sometimes “aerobic”) is the sort which gets your heart rate up and leaves you sweaty and out of breath. This includes jogging, brisk walking, swimming, cycling, and so on. The “cardio section” of a gym is where the cross-trainers, rowing machines and exercise bikes are. Cardio work is often contrasted with resistance (or “weights”) work. Doing cardio exercise burns energy, helping you to create an energy deficit and lose weight.


Cholesterol is a type of lipid (a type of fat found in the body). It’s a soft, waxy substance which comes from certain foods and which is produced by the liver. Saturated fats raise your cholesterol levels, but the polyunsaturated fatty acids linoleic acid (omega-6s) and linolenic acid (omega-3s) help to lower cholesterol levels.

Complete protein

A “complete” source of protein is a food that contains all 8 of the essential amino acids. (Think of amino acids as the “building blocks” of protein: when we eat protein, our digestive system breaks it down into separate amino acids.)


The idea of a “detox diet” is to rid the body of toxins, and advocates of detoxing list a number of benefits (increased energy, improved digestion, weight loss, boost to the immune system). Many doctors and dieticians, though, emphasise that the human body is perfectly able to expel toxins during normal day-to-day life and believe that “detox diets” have no beneficial effect.


Food is broken down during digestion so that it can be absorbed into the blood and used by the body. Your digestive system works from the point when you start chewing food to the point at which food is excreted from your body. Eating a healthy diet with plenty of fibre promotes good digestion – particularly regular bowel movements.

Energy deficit

In order to lose weight, you need to create an energy deficit. This means expending more calories than you take in. You can do this either by eating less or by exercising more – most dieters do a bit of both. (See the seventh part of the Dieting Basics series to find out how to calculate your daily calorie intake.)

Essential protein

There are 8 essential amino acids and 12 non-essential ones. Essential amino acids can’t be produced by our body and have to come from the food we eat. Non-essential amino acids can be manufactured by our body. (See the third part of the Dieting Basics series for more information about protein.)


In the UK, the government encourages us to eat five servings of fruit and vegetable per day. A serving is 80g, and you can’t count the same fruit or vegetable twice in a day. You can also only count one portion of juice per day. If you’re eating a healthy diet, it’s not hard to exceed the five-a-day target – remember it’s a minimum rather than an ideal. (If you struggle to get enough fruit and vegetables, here’s some fun ways to get your five-a-day.)


Found naturally in fruits, fructose is a monosaccharide (one-molecule) sugar. (See the first part of the Dieting Basics series for more information on fructose.)


We need glucose for energy – it’s the simplest form of sugar, and our body breaks down the carbohydrates we eat into glucose. It can also be found in foods, particularly energy bars and gels, and is sometimes known as dextrose. (See the first part of the Dieting Basics series for more information on glucose.)


The glycemic index (GI) ranks carbohydrates according to their effect on our blood sugar levels. High GI carbohydrates break down rapidly during digestion, whereas low GI carbohydrates that break down slowly and release glucose gradually into the bloodstream. The GI scale only applies to foods with a high carbohydrate content.


The glycemic load ranks carbohydrates based on both their GI (glycemic index) and portion size. A high-GI food consumed in small quantities would, in theory, have the same effect on blood sugar levels as a larger portion of a low-GI food. GL is calculated by mutiplying the weight in grams by the GI of a food, then dividing by 100.

Hydrogenated fat

Also known as “trans fats” or “transaturated fat”, hydrogenated fats are produced by a process called hydrogenation which turns vegetable oils into fats that are solid at room temperature. (See the second part of the Dieting Basics series for more information about hydrogenated fat.)

Insoluble fibre

The fibre known as “roughage” which helps keeps your stools bulky, is insoluble fibre. It isn’t absorbed by the body and passes straight through the digestive system. (See the fourth part of the Dieting Basics series for more information about insoluble fibre.)


Like the calorie, the kilojoule is a unit of energy. Calories are imperial units (standard in the US), whereas kilojoules are metric ones (standard in Australia). UK food labelling uses both, though popular usage prefers the calorie. There are 4.2 kilojoules to 1 calorie. (See the fifth part of the Dieting Basics series for more information about kilojoules.)


Found in milk and milk products, lactose is a disaccharide (two molecule) sugar. (See the first part of the Dieting Basics series for more information about lactose.)

Lean protein

Foods described as sources of “lean protein” are ones which contain a high percentage of calories from protein and few calories from fat. (See the third part of the Dieting Basics series for some examples of lean protein sources.)


A low-carboydrate diet restricts your daily intake of grams of carbohydrates; the Atkins diet is a well-known example. These cause rapid weight loss in the first few weeks, but have been associated with on-going health conditions and problems with maintaining weight.


Malted products, such as some breakfast cereals and types of bread, contain maltose – a disaccharide (two molecule) sugar. (See the first part of the Dieting Basics series for more information about maltose.)


The word “metabolism” covers all of the processes that occur inside your body to keep you alive. In dieting terms, though, “metabolism” and “metabolic rate” are used to talk about how many calories your body burns whilst at rest. People with a “slow metabolism” are those whose bodies tend to be most efficiency at using the energy provided in food – this makes it harder to lose weight. A “fast metabolism” can be promoted by building more muscle and by ensuring that your food intake doesn’t drop below 1,100 calories per day.

Monounsaturated fat

A type of unsaturated fat, monounsaturated fat is liquid at room temperature and solid when refrigerated. (See the second part of the dieting basics series for more information on monounsaturated fat.)

Obese and Morbidly obese

The official definition of obesity, sometimes called “clinical obesity” is a BMI of over 30. A BMI over 40 (in some cases a BMI over 35) is “morbidly obese” – this means there is a significantly increased chance of the person dying from causes directly related to their weight.


If your BMI is between 25 and 30, you are considered overweight. There are not significant health risks associated with being overweight, especially if you are reasonably fit – however, many people find that they are healthier when not carrying extra weight.

Polyunsaturated fat

A type of unsaturated fat and sometimes known as “good fat”, polyunsaturated fat is liquid at room temperature and liquid when refrigerated. (See the second part of the dieting basics series for more information on polyunsaturated fat.)


Dietary fibre is known as NSP (Non-starch polysaccharide) in scientific literature. In most popular dieting advice, you’ll see it referred to either as “fibre” or “dietary fibre” – or if you’re in the US “fiber” and “dietary fiber”. (See the fourth part of the dieting basics series for more information on fibre.)


Your Recommended Daily Allowance (RDA), known in the US as your Reference Daily Intake (RDI), is devised by the government. It’s the intake of a particular nutrient which is considered healthy for the vast majority of people, and is often printed on food labels. This covers intake of carbohydrates, protein, fat and fibre, as well as intake of individual vitamins and minerals.

Refined carbohydrates

Sugars are often known as “simple carbohydrates” or “refined carbohydrates” as they are quickly broken down by the body into glucose. (See the first part of the Dieting Basics series for more information on refined carbohydrates.)


Exercise which involves lifting weights for a number of repetitions (typically 12-25) is “resistance” work, as opposed to cardio. This is because it involves working the body against a resistance – a heavy weight. Resistance work builds muscle and helps to tone up your body.

Saturated fat

The type of fat considered “bad” is saturated fat, which is solid at room temperature. Too much of this will raise your cholesterol levels. (See the second part of the Dieting Basics series for more information on saturated fat.)

Soluble fibre

Unlike insoluble fibre, soluble fibre is used by the digestive system: bacteria in your colon break it down to create fatty acids which are thought to lower cholesterol levels. Soluble fibre also helps you to feel full for longer, as it slows the passage of food through the digestive system. (See the fourth part of the Dieting Basics series for more information about soluble fibre.)


Often considered the worst sugar nutritionally, sucrose is made up of a glucose molecule and a fructose molecule joined together. It’s usually derived from sugar gain. (See the first part of the Dieting Basics series for more information about sucrose.)


The term “superfood” is used for foods which have a high concentration of certain nutrients (particularly fibre, vitamins, antioxidents and which are considered particularly good for you. It’s not generally used by serious nutritionists, and can come across as a marketing gimmick.

Unsaturated fat

Unsaturated fats are liquid at room temperature, and are subdivided into monounsaturated and polyunsaturated fats. (See the second part of the Dieting Basics series for more information about unsaturated fat.)


A Very Low Calorie Diet (VLCD) is one which cuts calorie intake to under 800 per day. VLCDs should only be followed under medical advice, and you should not attempt one if your BMI is under 25.


Cereal products which use the bran and germ around the cereal grain are called “whole-grain”. These include brown rice, wholemeal (also known as wholewheat) flour, popcorn and oats. Whole-grain products contain more fibre, helping you to feel full for longer and boosting smooth digestion.


Some doctors and nutritionists use the “Waist to Hip Ratio” (WHR) to determine whether your weight is putting your health at risk. Weight stored around the waist has been shown put people at greater risk of heart problems and other health issues than the same weight stored elsewhere on the body.

Yo-yo dieting

Also known as weight cycling, yo-yo dieting involves repeatedly losing weight and gaining it back again. You might find yourself in this position if you go on an extreme diet which results in initial, rapid weight loss, but which you follow by “eating normally” again. The problem with yo-yo dieting is that you tend to lose muscle but gain fat. Yo-yo dieters often end up in poorer health than before they first attempted to diet.

I hope you’ve enjoyed the dieting basics series – I’ve had a great time writing it! I’m going to be publishing an ebook containing all the posts, and some extra content, soon: make sure you’re getting RSS updates so you don’t miss out…

  • Updated August 8, 2012
  • Basics

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