Junk food diet

Junk food definition

Junk food is defined by wikipedia as " food that is of little nutritional value and often high in fat, sugar, and calories". I don't think this definition tells us enough. Most people have a conception of what junk food is, and that normally includes some degree of food processing, as well as the presence of some undesirable industrial additives in addition to the characteristics in wiki's definition.

Let's look at some of the characteristics that classify a food as junk.

Nutritional value

This implies that a food contains little in the way of micronutrients. That is the vitamins and minerals our bodies need in order to function properly. Of course we also need the macronutrients: protein, fat and carbohydrate, which are in fact supplied. As such if you found yourself on a desert island with no food, then a MacDonald's burger would sustain you better than nothing. Equally a can of coke would provide the energy to go and look for some other food on the island. Nevertheless, most of us are not in danger of deficiency of the macronutrients (protein. fat and carbohydrate) and so junk food has nothing to offer us. Rather the opposite in fact as unfortunately many of us are deficient in the micronutrients. Junk food has very little of these vitamins, minerals and healthy phytonutrients (plant nutrients). As a result many kids brought up on junk food are deficient in vital nutrients that are needed for growth, brain development and good health.

High in fat

This is a fairly broad definition that covers very healthful foods, such as salmon, as well as unhealthy foods such as vegetable oil. The reason many of the so called junk foods are full of fat is that, oils and fats are responsible for making the food have a better mouth feel.  For instance, it can make foods more satisfying and give them a creamy texture. Of course being high in fat does not automatically make a food unhealthy. The type of fat is important, and it is the processed fats that are the worst for health. Unprocessed fats, whether saturated or not, are needed for good health and our bodies cope with them fairly well, unless we eat one type almost exclusively at the expense of another. Junk foods unfortunately feature many of the unhealthy processed fats, particularly trans fats and interesterified fats.

High in sugar 

This is a fairly specific definition, and ignores the fact that most starches (bread, pasta, rice, potato etc) break down into sugars in our guts. Any sugar that is absorbed into our bloodstream has the same sort of effect. However, as with fats, carbohydrate in the form of sugar, is used to make food more satisfying, by making it sweeter. As with fats a little sugar is not going to do any harm, and nor for most people will a little starch, unless they are allergic to the form of starch they are eating. Eating a lot of carbohydrate, whether sugar or starch will often destabilise blood sugar levels and this can have a harmful effect on long term health.

High in calories

This implies that the food is actually calorie dense. Calories are most dense in fat 9kcal/g, followed by alcohol at 7kcal/g, and then protein and carbohydrate including sugar at 4kcal/g**. Many people assume that sugary foods are high in calories, whereas the opposite is in fact true. What needs to be added to the picture however, is how much water a food contains. If a food has a lot of water then it will contain fewer calories per gram than a dry food. What you see with many typical junk foods, is that they are often quite dry, necessitating the use of drinks at the same time. All part of the food industry's clever game of making us consume one junk food (burger and fries), and then require another one (coca cola), just to wash it down. Compare this with fruit and vegetables which are normally full of water and therefore contain fewer calories by weight.

**In case you are wondering why I use kcal/g (kilocalories/gram) and then talk about calories, well that is because we nutritionists use the word calorie to mean kilocalorie. I'm just following my profession's conventions!

Now the wiki definition leaves a lot to be desired as I mentioned at the top. We need also to consider that the vast majority of junk food is processed and has additives added in. Natural foods just don't figure in the junk food universe. Processed foods often come in packaging and a junk food free diet will contain very little food in tins, vacuum packs, jars, bottles, cling film and cardboard. Additives are very common in junk foods and the longer the list of additives the higher the chances that the food is unhealthy. One additive that is commonly used is salt. It is used, like sugar, to create an addicition to the food. While salt naturally occurs in some foods its addition to soups, cereals, ready meals and a host of other packaged foods is a sure sign of a junk food.

The layman's guide to what is junk food.

  • Is the food in a package, jar, bottle or tin? If so, it's more likely to be junk food.
  • If the food is in a container of some sort, is there a list of ingredients as long as your arm? Again, this is a giveaway that you are looking at junk food.
  • Does the food contain > 4mg of salt per 100g or > 9g of sugar per 100g. If this is so then the product you are looking at has a lot of salt and sugar added to seduce the consumer into consuming too much of it.
  • If you are eating out does your food come in a container. It's probably junk.
  • Are you drinking something with more than 8% sugars by volume. Most fizzy drinks jump straight into this category.
  • Are you drinking something with artificial sweeteners in it. It's junk!

Common junk foods include crisps, shop made cakes, muffins and biscuits, chips and ready meals. Home cooking normally ensures that your junk food exposure is reduced. However, avoid ready made sauces. If you can make all your sauces, use plenty of vegetables and buy your meat and dairy from a reputable butcher you will be getting towards being junk free. Notice that this is pretty much what your grandparents did? Well back before the 2nd world war junk food was not so available and obesity was virtually non-existant. This is not a coincidence. Junk food is designed to seduce the consumer into eating more, and it often contains plenty of carbohydrate, which can destabilize blood sugar levels and encourage the build up of round the waist.

Junk food and health.


Junk food is bad for health. Of course that is a generalisation as junk food covers a lot of different foods, but it is true for the vast majority of food that could be described as junk. One reason, as stated in the definition of junk food at the beginning of this article is that junk food contains little in the way of vitamins and minerals. If you eat too much junk food you leave less space for foods containing these vital vitamins and minerals. The result is you become deficient in many of them, and this leads ultimately to poor mental and physical health.


Another problem with junk food is it is designed by food companies to make us want more, and this leads to obesity. It is completely accurate to say that junk food is the leading cause of the worldwide obesity epidemic. It is of far more importance than lack of exercise, or the relative amounts of carbohydrate, fat or protein that you eat in your diet. You may argue that you've seen evidence that it is possible to lose weight on a caloire controlled junk food diet1. The problem is that calorie controlled diets rarely lead to weight loss in the long term as people invariably return to their previous ways of eating. Most people who are obese find it difficult to control their appetite, and junk food is designed to increase appetite. Losing weight permanently on a junk food diet is an almost impossible task. 

Mindless Eating.

A third problem with junk food is its association with mindless eating. Most of this type of food is eaten, either on the move, or more likely in front of the TV. Watching TV has been shown to consume less energy than being asleep, so your surplus of calories is likely to be amplified. Eating on the move, or slumped in front of the TV, will not encourage the digestion to work properly, leaving more of your foods in an undigested state. You will be far more likely to suffer with indigestion, and will absorb less of the few nutrients that are available in the food. Junk food TV adverts could create a viscious circle of increased junk food consumption, especially if children are eating in front of the TV.

You may point out that many top olympic athletes eat heaps of junk food2. However, you'd be failing to look at the long term picture. Many of the reports of excessive consumption of junk food relate to swimmers. If, like me (a coach of triathlon) you've come across retired swimmers, retired cyclists and retired runners you'll have noticed how the people who ate the junk foods are the ones looking decidedly unolympic when they reach 50 years of age. Swimming is definitely a sport with a problem in this regard with a greater percentage of obese parents than in other sports.

Junk food and the environment.

Junk food is bad for the environment without a doubt. When it is produced energy is used to create packaging. The foods and additives that are used in most junk foods also require more energy to produce than fresh foods. The packaging then gets left in the trash to litter the planet for the next few generations.

At a less obvious level, junk food creates a society of fat people who are less likely to do exercise, and will need to heat their homes more, despite their extra layers of insulation. On average they will use petrol burning vehicles for more of their journeys, and will spend more time with electronic gadgets turned on than people who don't eat junk food. You could argue that people cooking their own food are going to use more energy in the kitchen, but this is likely to be completely offset by the amount of energy that was used to produce the junk food in the first place.

Weaning yourself off junk food.

It is very difficult to take a half way house with junk food. Unless you are suffering from serious withdrawal symptoms I suggest you try to eliminate elements of your junk food diet, completely one at a time. That is not to say that you need to become junk free immediately. What I'm suggesting is that you decide which source of junk food you are going to eliminate, and then completely eliminate it. Here are some examples:

  • You go to a popular junk food outlet (let's call it McCampbell's), twice a week. Just replace the visit with eating at home or going to a sit down restaurant with food on a plate. You could argue that you will still go there but eat more healthy foods instead. There are two reasons that it is likely to be ineffective to still visit McCampbell's. Firstly, if you are taking kids or even yourself, there is always going to be the temptaion to eat the old unhealthy foods again. Secondly, the healthy foods at McCampbell's are not as healthy as you might think. Orange juice versus coca cola? Not much difference. Wholewheat bun versus French fries? You will still be struggling to eat foods that will reduce your weight. The effect of the bun on your blood sugar levels could be as high as the chips.
  • You eat a ready meal every Wednesday. Don't replace it with anything in a package whether it is low fat, free of additives or low sugar and salt. Replace it with a home cooked meal prepared with fresh ingredients. We are only talking about once per week. If you are serious about your health, then you have to be prepared to make an effort. If you are not prepared to put in any effort then there are no magic cures!
  • You drink a can of coca cola after every squash game you play. Replace it with water and ensure you have a balanced meal within a few hours of finishing the game. A squash game lasting up to 1 hour should not deplete your blood sugar levels to the extent that you need to take in sugar either during or immediately after the game. Your body will soon learn to handle its blood sugar levels far better, if you do not regularly consume sweet fizzy drinks or indeed fruit juices every day.

Bear in mind that once you've been without a food for a reasonable period of time, the chances are that you will not crave it any longer. The other factor to consider is that the cues that lead you to eat junk food need to be removed to be successful. So that could mean, not having certain foods in the house such as crisps, avoiding visits to certain eating establishments and not eating in front of the TV.

DrDobbin says:

As you can tell I'm not a fan of junk food. I'd encourage you to remove it from your diet and experience the benefits. It may involve some effort, even a lot of effort for some, but as with most things in life the more you put in the more you will get out.


1) http://www.mayoclinic.com/health/junk-food-diet/MY01589

2) http://online.wsj.com/article/SB1000087239639044413030457755925308734652...