Calories, Calories, Calories!
5 facts to remember about calories
Growing up I remember my mother and my aunties always having at hand a calorie book. I actually remember how it looked like, it was the size of a palm, red and inside it listed all the food calories. I do also remember how even just a kid back then, I have memorised so many foods. However, times have changed and now counting calories is often mentioned as a misinformed and old method to maintain and lose weight. Calories do count though; as the simplest fact to remember is that when your calorific intake is higher than your energy expenditure you gain weight. So maybe count this as your basis fact calories are calories. However, it is also accurate that not all calories are the same. In order to clarify the truth about calories I have selected 5 scientific facts that you need to remember when you think about calories!
As “threpsis” means nourishment in Greek it is not surprising that I will start with the nourishing aspect of calories. When you eat, you fuel your body with calories but the quality of your life depends highly on what those calories offer you. Alcohol, processed sugary/fatty foods, fizzy drinks contain empty calories! They are not nourishing to your body. A can of a popular fizzy drink contains 140 calories, whilst a tablespoon of almond butter with a small apple also contain 140. The one choice nourishes you with vitamins and minerals while keeping you fuller for longer while the other provides you some caffeine and sugar and makes you crash after an hour… The choice is yours.
The energy output is heat released by the body though basal metabolic rate (BMR), physical activity and adaptive thermogenesis due to various environmental stimuli (such as diet-induced thermic effect and thermogenesis by adaptation to the heat or cold) [1, 2].
Therefore, the energy intake (calories) somebody needs is highly dependent on the energy expenditure. An athlete will not require the same calories as someone living a sedentary life. However, it is very important to highlight that quite often we overestimate the calories "burnt" due to physical activity.
For children, it is important to remember that during periods of growth they require more energy and calories. Mums may notice an increase in appetite during growth spurts in infants. While adolescents may need to change their nutrition in order to respond to increasing energy requirements.
Similarly, pregnant women require 200 kcal more to accommodate the growth of the growing fetus. Of course this may be different for overweight mums. Also, 200 kcal are very easy to meet and it is important to remember not to eat for two but get nourishment for two.
The thermic effect of foods
You may have come across this term, which unfortunately is often used wrongly in many blogs and web pages. Diet-induced thermogenesis (DIT) or alternatively, the ‘thermic effect of food’ is the amount of energy consumed in the process of digesting, absorbing and metabolising nutrients . Different macronutrients require different amounts of energy to process and thus produce differing amounts of calories through thermogenesis [4, 5]. This is how high protein diets work because to thermic effect of 1 g of protein is greater to the calories it provides. Therefore, if theoretically you only consumed protein you would end up with a negative energy balance (of course you would feel unwell after a while). So even if you get the same calories from a steak and a bowl of white pasta with sauce your body will “burn” more calories to metabolise the steak. The same would stand for the previous example regarding the fizzy drink.
Nowadays, there is this trend that whatever is natural, healthy and unprocessed, it is also “guilt-free” and I believe this may lead us to the same situation “diet-foods” lead us two decades ago; to an increase of the obesity rates worldwide. No matter how “good for you” a food is, when you consume larger quantities of it you will gain more calories. So if the tablespoon of peanut butter becomes one and a half then you increase the calories. If you add a teaspoon of honey to your porridge it wouldn’t be the same as adding a tablespoon. Actually, this is particular important when it comes to sugars/sweeteners (natural or not) as even if the glycaemic index of maple syrup (for example) is lower than this of sugar if you use larger quantities it will have the exact same effect on your insulin response as white processed sugar would (more to come on sugars soon).
It is very easy during the day to gain more calories just by slightly underestimating your portions. Therefore, it would be useful to use measurement spoons/cups if you find hard to understand the optimal portions. Also, make sure to read your food labels carefully as sometimes in one package more than one portions are included.
The aftermath of calories
It is not only important how many calories and nutrients a food may have but also how it affects our bodies after we eat it. This is a very complex issue and relates to some of the points raised above but I will not expand much in this blog.
Food can affect the production and secretion of hormones by direct actions on the gut, by nervous reactions, through concentration changes of various metabolites in the blood, or by influencing the circulating gut hormone levels . The effect of a food can either induce the feeling of satiety or not and also influence rewards systems in the brain that may induce the consumption of unhealthy foods .
A diet rich in fats and sugar has been shown not only to provide little to no satiety but also to activate brain reward pathways. On the contrary a diet rich in fibre and protein has been linked with increase satiety and no impact on the brain reward pathways. Therefore, engaging to a diet rich in fibre coming from fruits, vegetables and whole meal starch would only make you feel fuller for longer during the day but also help you make healthier meal choices in the long-term.
I hope these facts provide a good idea as to what you need to consider when you are looking at food labels or your latest food tracking apps. The take-away message? Always aim to get the most out of your calories! Aim for foods that will help you feel full for longer, nourish your body and satisfy your taste buds!
1. Geissler, H.P.a.C., Human Nutrition. Eleventh ed. 2005: Elsevier.
2. Groff, J.L. and S.S. Gropper, Advanced Nutrition and Human Metabolism. 3rd ed, ed. L. Graham. 2000, Belmont California: Wadsworth. 584.
3. McArdle, W.D., F.I. Katch, and V.L. Katch, Essentials of exercise physiology. 3rd ed. ed. 2006, Philadelphia, Pa. ; London: Lippincott Williams & Wilkins.
4. Westerterp, K.R., S.A. Wilson, and V. Rolland, Diet induced thermogenesis measured over 24h in a respiration chamber: effect of diet composition. Int J Obes Relat Metab Disord, 1999. 23(3): p. 287-92.
5. Westerterp, K.R., Diet induced thermogenesis. Nutr Metab (Lond), 2004. 1(1): p. 5.
6. Marks, V., How our food affects our hormones. Clin Biochem, 1985. 18(3): p. 149-53.
7. Carreiro, A.L., et al., The Macronutrients, Appetite, and Energy Intake. Annu Rev Nutr, 2016. 36: p. 73-103.