The science behind calories is simple, says Karen Emerson as she argues that we should start viewing our food as essential meals and not a way to lose weightIn the face of the obesity epidemic, we have become calorie obsessed. In a bid to regain consumers’ trust, food companies have resorted to putting the calorie content of their products on menus, on websites and firmly into our consciousness when choosing what to eat.How important is a calorie? What does it mean? Is our calorific equilibrium, or inequilibrium as the case may be, the reason we are the size we are? For something that has become so central in public health consciousness, many people know surprisingly little about what a calorie actually refers to.In brief, a calorie is the amount of energy needed to raise one kilogram of water one degree Celsius. To measure the calorie content of a specific food, the food sample is burned in the presence of oxygen in a bomb calorimeter.The rise in temperature correlates to the amount of calories, or more correctly kilocalories, in the food. This method was originally introduced by French physicist Nicholas Clément in the early 19th century during lectures describing heat engines.The question obviously arises: how relevant is this to the metabolic processes that occur in our bodies? The answer is perhaps not very. Our bodies are not simple heat furnaces. Each macronutrient is treated differently by our digestive systems and triggers individual sequences of events that will have varying effects on how our bodies look and feel.We are taught that to maintain a healthy weight our energy input (the food we consume) must equal our energy output (energy for normal body functioning), thermogenesis (energy required to digest food), and physical activity.The equation for a svelte physique could not be simpler, yet in Ireland the Department of Health states that 39% of Ireland’s population are overweight and almost a fifth of the nation is obese.Considering that in 2013 a record number of runners competed in the Dublin marathon and we are currently undergoing a cardio and cross-training revolution similar to that of the 1980s, it is difficult to comprehend how the population’s health is deteriorating faster than an eight minute mile.In an effort to promote healthy eating and to steer the public away from high sugar foods, which in excessive amounts are known to lead to type 2 diabetes, public health officials have warned us from indulging in ‘empty calories’. This insinuates that it is not the calorie content that is the problem, rather what they are lacking, such as vitamins and minerals.However, it is the content of these ‘empty calories’ that drive weight gain for many people. Dr Robert Lusting, paediatric endocrinologist in the University of California and author of Fat Chance; The Bitter Truth About Sugar, was one of the first high-profile health professionals to declare that “a calorie is not a calorie.”Dr Lustig has since become a YouTube sensation with his 90 minute scientific lecture on sugar and the metabolism of fructose gaining over four million views; a clear indication that the ins and outs of nutrient breakdown and their effects on the body not only interests the scientific community.A recent UK government study found that the British population is consuming up to 600 less calories per day than their counterparts 30 years ago. Somewhat counter-intuitively, within the same timeframe Brits have gained an average of eight kilograms each. The latest stats from the NHS claim that over 60% of women in the UK are considered to be overweight.The proof is in the pudding, as is the weight gain. The same study also found that British people today consume almost 70% more calories outside the home than in 1980. While Ireland’s figures may not have reached the same dramatic heights yet, it can be assumed that we will soon follow our neighbour’s footsteps.Despite having clear, concise dietary guidance, the obesity epidemic has become an international crisis, with babies as young as six months old being diagnosed with type 2 diabetes. All parts are not equal when it comes to food consumption. So it’s ‘you are what you eat’ rather than how much you eat.For example, wholemeal products have higher calories than their more processed versions, yet your digestive tract will thank you in years to come for providing extra fibre in your diet which reduces the risk of bowel cancer and diverticulitis. Food intake is the one aspect of our health that we can improve instantaneously and feel the benefits from often immediately.Our diet is more than just a numbers game. If we become less concerned with striking the elusive balance between energy input and expenditure, we can start to view our meals as essential fuel that will help us ward off both physical and mental illness.Focussing on the inclusion of healthy foods rather than a restriction to 1800 – 2500 kcal per day can promote a healthier food ethos, which inspires a more positive relationship with food and encourages a hands-on, home-cooked approach. Foodies have no fear; health is not synonymous to hunger.