There are four laws of the universe. We can largely ignore the zeroth and the third in the world of dieting. The two that we need to take into account are the first and the second and neither of these says energy in equals energy out.

The first law says:  “In a closed system, in thermal equilibrium, energy can neither be created nor destroyed.” Energy can be changed from one form to another, but it shall be conserved. The human body, however, is not a closed system and it is not in thermal equilibrium (although it is continually trying to be there). So, we also need to consider the second law.

The second law (entropy) has been called the law of common sense – it says that energy will be lost and energy will be used up in making available energy and we need to take both of these into account. This is the law that proves that a calorie is not a calorie, as even Weight Watchers cottoned on to with their launch of ProPoints in November 2010. The energy used up in making carbohydrates, for example, available to the body as energy vs. the energy used up converting protein to usable energy is substantially different. 100 calories of carbohydrate eaten may make 93 available to the body; 100 calories of protein eaten may make only 70 available (Ref 1). That’s a significant advantage for dieters and helps to explain the effectiveness of low carbohydrate diets.

These ‘laws of the universe’ were developed during the industrial revolution to help understand if we could make a perfectly efficient steam engine. The laws were and are all about energy, not weight. The laws say nothing about weight being conserved – we humans flit between energy and weight interchangeably in the world of dieting and our conversions and assumptions are wrong.

The laws of the universe were never intended to become the fundamental principles of dieting. They do have some relevance to dieting, but only when they are correctly applied and when all the caveats are allowed for. There is simply no law that says energy in equals energy out. Even if there were, the corollary would surely be – less energy in equals less energy out, which brings us nicely to the second piece of knowledge…

Ref 1: Jequier, “Pathways to Obesity”, International Journal of Obesity, (2002). (See reference 29 on The Obesity Epidemic)

It is an almost universally held belief that people who are overweight just need to eat less and/or do more. The idea that eating less will make you weigh less assumes that the body cannot and does not adjust. It can and it does. To think that if you eat 500 fewer calories the body will give up 500 calories of fat, to make up the difference, is the ultimate naivety in the world of dieting. The body is not a cash machine for fat.

Let us say that our average person has a basal metabolic rate (BMR) requirement for 1,500 calories a day (the number of calories the person would need if they were ill in bed all day – just to run all the activities done by the body). Let us then say that they have a requirement for 500 additional calories if they are up and about (this is a realistic estimate – the BMR is the main determinant of the calorie need for the day by a margin).

The idea that a reduction of 500 calories leads to the body giving up 500 calories of fat assumes that neither the BMR requirement (1,500 calories) nor the additional requirement (500 calories) changes. In reality both change. The person who eats less has less energy and they will likely do a less additional activity that day – they won’t go to the gym or walk to the post box – they will be too tired. The body will also cut back on its maintenance for the day – it can save cell repair, fighting infection and building bone density for another day – you haven’t eaten enough, so it can cut back.

Think about it – you lose your job – you don’t automatically dip into savings – you cut back on expenditure and the body does exactly the same.

The exact same applies for doing more. If you think that you can eat the 2,000 calories needed for the day and then try to do 500 more calories worth of exercise, with the body making no adjustment elsewhere, you are wrong. The body is highly likely to cut back on the additional calorie expenditure above the BMR. If you go to the gym, you may then sit on the sofa all evening – too tired to do the housework. The body can also reduce the maintenance it had planned to do for that day.

Furthermore, exercise and BMR require quite different calories. Exercise is arguably best fuelled by carbohydrates (it provides glucose quickly for the body to use). BMR activities need fat, protein, vitamins and minerals. Carbohydrates can be useful for the vitamins and minerals they provide, but the macronutrient, the carbohydrate itself, can only be used for energy – not cell repair and fighting infection. Hence – if you eat 1,500 calories of carbohydrate (as the average citizen of the developed world currently does) – it can’t be used for body maintenance – you need to burn if off down the gym or you will gain weight.

Both the eating less and doing more beliefs also make the massive and wrong assumption that the body is able to burn fat. The body will always use carbohydrates for fuel first. Hence, if our average person has any glucose in the bloodstream or any glycogen (stored glucose) in the body – this will be used to cover any gap in food eaten or activity done. The body can only burn fat when there is no glucose/glycogen available. A modern man rarely, if ever, allows his body to get to the state where it can burn its own fat – let alone will.

Eating less makes us want to eat more and/or do less. Doing more makes us want to eat more and/or do less. Neither eat less nor do more has worked, can work, or ever will work as a solution for the obesity epidemic.

1. Avoid fast food deliveries

It is almost certain that in fresher’s week you will be bombarded with flyer after flyer of fast food offers, all claiming that they can offer amazingly cheap deals to students. Companies such as Dominoes and Deliveroo thrive off students who don’t know how (or can’t be bothered) to cook after a busy day at uni. However, frequently buying food from these fast food chains is not only bad for your health, but will also bite a huge chunk out of your weekly budget. Let’s put it this way; if you ordered a medium pepperoni pizza from Dominoes it would come to a total of £15.99. That’s equivalent to a whole chicken, a pack of minced meat, 12 eggs, a pot of soup, a loaf of multigrain bread, a bag of quinoa, a litre of milk, a bag of cous cous, 6 apples, 6 tangerines… oh, and a deep pan pepperoni pizza from Aldi. Once you start comparing these ‘amazing’ student deals to the price of food in supermarkets they suddenly start to sound less ‘amazing’.

2. Compare different supermarkets

Whilst at university, the supermarket should be your best friend. Having said that, not all supermarkets are made equal and some may be much pricier than others. Safe bets for your weekly shop would be places such as Aldi, Lidl and Morrisons that pride themselves at balancing good quality with affordable prices. Supermarkets to steer clear of may include Waitrose and M&S (save those for grownups with actual incomes!). If it just so happens that the nearest cheap supermarket is a 7-hour trek up a snowy mountain, through the dark woods and across the blistering desert then consider doing an online grocery shop. They’re usually very useful as you:
– Won’t be tempted by all the chocolate near the till
– Can do a shared order with your flatmates, making delivery costs next to nothing!

3. Flat dinners for the win

Flat dinners usually work extremely well. Not only do they get everyone involved and having fun cooking together, but it also works out as much cheaper when the cost of ingredients is split between everyone. For example, a big ol’ chicken curry shared between 6 people will easily come to less than £2 each! Making a meal from scratch will be much healthier than eating a ready meal or going out to a restaurant as you know everything that goes in, meaning it won’t contain any nasty additives or hidden calories (yay!). Some examples of healthy crowd-pleasing group meals that are bound to get everyone licking their lips include fajitas, stir fry, Thai curry, pasta bake, one pan rice and soup.

4. Be the meal prep master

So, you’re making a pasta vegetable dish for dinner and you measure out the perfect amount for one portion because you’re the only one eating it tonight. The next day lunch time rolls around and you head to the shop to buy your daily meal deal. Eating habits like this are extremely common but you could save £21 a week by bringing in leftovers instead! Making double the amount of dinner won’t cost much more and requires less effort than buying lunch every day. Furthermore, if you have food prepared in advance, then you are less likely to pick up something unhealthy from the shop. So, consider investing in plastic food containers and start nailing your lunch game whilst saving money at the same time.

5. Use social media to your advantage

One thing that proves to be extremely helpful and accessible to students eating healthy on a budget is social media. Facebook contains many pages dedicated to cheap, healthy recipes for students – some examples include EDY Yann. Instagram is another useful source for cheap, healthy meal inspiration. Filling your newsfeeds and social media with these kinds of pages will hopefully motivate you to put that little bit of extra effort in and make nutritious, affordable meals, while also realising that cooking can be satisfying and enjoyable!