Questions about diets

Do you ever find yourself wondering which is the most effective way to “diet”? Well here is the truth: many different diets work for short-term weight loss1. If you consume fewer calories than you burn each day, you will lose weight over time16. It is that simple. You could even eat a diet of just chocolate if you wanted to, providing you were in a caloric deficit, and still lose weight. Of course, this is a terrible idea as you would be missing out on 99% of vital nutrients, you would struggle to feel full and you’d be eating a lot of sugar.


But the point still stands – energy out must exceed energy in. Nevertheless, the adjustments you make to your relative intakes of fat, protein and carbohydrate should reflect the requirements of your daily activities. If you lift weights regularly, you need plenty of protein. If you are a runner, you need adequate amounts of carbohydrates, and so on.

I personally do not prescribe to a particular “diet”. Scientifically speaking, diets do not work long-term2, changes in behaviour and hence lifestyle do. It isn’t any one type of food that is the problem, it is your relationship with that food. This is why I focus on helping my clients to change their approach to nutrition. If you can change your behaviour, food no longer becomes a problem, and you are in control of your eating patterns whilst being able to enjoy yourself. Exercise also plays an important part in keeping fit and healthy. But that is for another post; here I want to talk about dietary decisions.

I am not going to go through the pros and cons of all of the various diets out there, partially because it would take too long but also because I have not tried them all myself. However, I want to talk about some useful findings from recent research that help to answer common questions about diets. I plan to address more specific factors individually in future posts.

Do I have to be strict 100% of the time?


Intermittent dieting strategies can be just as effective as constant restriction3. So if you prefer to take the pressure off by breaking up your diet with short periods where you don’t restrict yourself as much, fear not – you can still get results, and it may even make it more psychologically manageable for you.

In fact, compared to very restrictive approaches, flexible approaches to dieting are associated with greater weight loss success, less over-eating and lower levels of negative psychological symptoms such as feelings of anxiety or depression4. From an intuitive point of view (as there aren’t many studies on this specific matter), this isn’t surprising. Flexibility allows more room for enjoyment, making your diet more sustainable and less stressful.

Perhaps this explains the success of the popular “flexible dieting” protocol, otherwise known as “if-it-fits-your-macros” (IIFYM). It allows you to be flexible in your choices while fuelling your body with personalised proportions of fats, proteins and carbohydrates to suit your activities and preferences. Of all the diets, this is the one that makes the most sense to me personally. It is also possibly the easiest to adopt as a long-term lifestyle if you struggle to cut things out.

How much fat, carbohydrate and protein?

Most diets today focus on altering the proportion of macronutrients you consume, i.e. fats, proteins and carbohydrates. A recent study investigated the effects of four different diets on weight loss, each containing different proportions of macronutrients. Over a period of two years, all four diets produced the same levels of weight loss and ratings of fullness1. Essentially, reducing fat in your diet is effective for weight loss5, just as reducing carbohydrates can be6. Various systematic reviews have found that low-carbohydrate diets are equally as effective as balanced diets7 and low-fat diets8,9 for weight loss.

Some people and indeed researchers will argue that low-carbohydrate diets are more effective. However, other studies have found low-carbohydrate diets to offer no benefit over conventional diets, particularly in the long-run; and by cutting your carbohydrates too much you may miss out on nutritious grains, fruit and veg14.

What is more important than the ratio of carbohydrates to fats is the quantity of protein that you consume. Firstly, protein is highly satiating, i.e. it makes you feel full – this means you are less likely to continue eating once you’re done with your meal. Secondly, protein boasts a higher thermic effect than fat or carbohydrate10, meaning that the protein digestion process uses more energy and hence slightly more calories. Thirdly, protein is vital for building and maintaining muscle, something that is essential if you want to get fit and stay fit.

In reality, the most important factors when going on a diet are choosing wholesome ingredients and your personal preferences. There isn’t enough research out there to confirm whether favouring any one macronutrient is healthier than the other in the long-run, and for whom. Some studies have suggested that low-carbohydrate diets may produce slightly more favourable blood lipid profiles9, however meta-analyses have found that this may be counteracted by other negative effects on cholesterol11,12, and other potential cardiovascular risks in certain populations13.

So, while we know that low-carbohydrate or low-fat diets work for weight loss, the lack of certainty around health effects suggests that the best strategy for your long-term eating habits is likely the not-so-glamorous “everything in moderation concept.

More on carbohydrates and sugar….

A lot of people will tell you that carbs and sugar are your enemies. They can be – if you eat them in excessive amounts. Equally, excess protein and fat doesn’t do you much good either. I return to the not-so-sexy idea of everything in moderation. Sorry, not very interesting, I know.

photo3Carbohydrates are essential if you are doing vigorous exercise. They help fuel your activities so you can work at a high intensity, and they replenish your glycogen stores once you are done, meaning you recover as efficiently as possible for the next session. Also, whilst the idea of protein being vital for building muscle is probably one of the most universally known facts about exercise nutrition, people often overlook the fact that CARBOHYDRATES are also necessary to build muscle. And of course, they will help fuel your weights session.

Even sugar itself is not something to be afraid of. A recent systematic review of relevant studies found that while cutting down on sugar can indeed lead to weight loss, substituting other types of carbohydrate for sugar actually led to no changes in body weight. The authors concluded that weight loss due to cutting back on sugar is likely due to the REDUCED CALORIE INTAKE rather than the metabolic processing of sugars15. The bigger issue is that “processed” foods high in sugar (e.g. cakes, biscuits, sweets, reduced-fat foods) are often high in calories and devoid of vitamins and minerals, so you are consuming calorie-dense foods that really offer you no benefit apart from energy. And again, if most of your diet is made up of these, you will be consuming sugar excessively.

In addition, research has shown that regular exercise not only attenuates any negative effects from diets high in sugars such as fructose17, but also improves insulin sensitivity18. In a basic sense, insulin is the hormone that facilitates the uptake of glucose from the carbohydrates you eat into your muscle cells, where it is stored as glycogen. Essentially, it helps to keep your blood sugar levels balanced, reducing the amount of excess glucose available for fat storage. So if you are more insulin-sensitive, glucose will be efficiently taken up by muscle glycogen stores in response to little insulin, resulting in balanced blood sugar levels and less fat storage. This is just one reason to exercise regularly! But the point is, sugar isn’t as harmful as you think it is in moderate quantities.

What REALLY matters is that you are consuming wholesome, nutritious foods that are beneficial to your healthThis means picking foods that are as natural as possible, without the presence of nasty additives. BUT that does not mean that everything you eat has to be in its natural form. I generally go by the rule that you want as few chemicals/additives as possible, rather than going for “minimally processed”. The problem with the word “processed” is that a lot of very nutritious foods are technically processed, but it doesn’t mean they aren’t healthy. I enjoy eating buckwheat pasta, 100% almond butter, natural Greek yogurt and quinoa – all processed, but nutritious without nasty additives.

Focus on your own journey

Finally, don’t be unsettled by what other people are doing. Whatever you do should involve as little stress as possible while maintaining your health. Everyone is different; what works for some people may not work for you, and vice versa. The best dieting strategy for you will depend on a number of things such as time, budget, goals, taste preferences, activity levels and even body type.

Just because someone you know is on a “clean eating” diet, for example, it does not mean that a) you should too and b) it is the right way to go about things. As I said before, the problem is not the food, it’s the amount you eat it in. Bananas are a lovely nutritious fruit, yet they can be poisonous if you eat enough of them. So is water in high doses!!! It just takes smaller amounts of certain foods to harm your health than others.

But if you like the idea of “clean eating”, then by all means go ahead. Essentially, you do not have to follow any particular diet to achieve awesome results, you need to find what works for you. The idea of “everything in moderation” is certainly not obsolete, as evidenced by the people who use flexible dieting.

I have a real sweet tooth – I eat chocolate regularly and I love baking treats like brownies, cookies and cakes, using normal flour and butter.

Newsflash: you can do this and still be healthy, providing you are getting nutritional value from the rest of your diet. The reason that my love for all things chocolatey makes no difference to my athletic performance or physique is that I am mindful about how I eat things. For example, I consume a lot of the sugary foods in my diet immediately after track sessions or long runs, to shunt the glucose into my glycogen stores. [Tip: consuming a high-carbohydrate snack within half an hour of finishing intense exercise can reduce the likelihood of cravings later on in the day!]

It also goes without saying that the more you exercise, the more calories you can consume and hence the more freedom you will have with things like chocolate. This is not to say that you should go crazy with the chocolate every time you exercise, but you get the gist. Equally, you do not have to exercise vigorously every single day to enjoy a treat! You just have to be aware of your choices, and make sure you are fuelling your body with nutritious foods on the whole.

And indeed, if you want to totally cut out things like chocolate and adopt a plant-based diet free of refined sugars, then fantastic. At the end of the day, it’s about your individual needs and preferences.

Take-home points:

  • Most diets works for short-term weight loss – just make sure you are getting sufficient amounts of each macronutrient, and plenty of vitamins and minerals.
  • Your activities will dictate to a degree the relative amounts of fat, protein and carbohydrate you need.
  • Allow yourself some flexibility for sustainability and your sanity.
  • Include quality sources of protein with every meal.
  • Opt for natural or nutritionally dense foods where possible.
  • Get moving – it helps to create a calorie deficit without drastically reducing what you eat, but also brings a whole host of health benefits such as better tolerance of sugar.


  1. Sacks, F. M., Bray, G. A., Carey, V. J., Smith, S. R., Ryan, D. H., Anton, S. D., McManus, K., Champagne, C. M., Bishop, L. M., Laranjo, N., Leboff, M. S., Rood, J. C., de Jonge, L., Greenway, F. L., Loria, C. M., Obarzanek, E., & Williamson, D. A. (2009). Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. The New England Journal of Medicine, 360, 859-873.
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  6. Hashimoto, Y., Fukuda, T., Oyabu, C., Tanaka, M., Asano, M., Yamazaki, M., & Fukui, M. (2016). Impact of low-carbohydrate diet on body composition: Meta-analysis of randomized controlled studies. Obesity Reviews, 17, 499-509. doi:10.1111/obr.12405
  7. Naude, C. E., Schoonees, A., Senekal, M., Young, T., Garner, P., & Volmink, J. (2014). Low carbohydrate versus isoenergetic balanced diets for reducing weight and cardiovascular risk: A systematic review and meta-analysis. PLoS One, 9, e100652.
  8. Brinkworth, G. D., Noakes, M., Buckley, J. D., Keogh, J. B., & Clifton, P. M. (2009). Long-term effects of a very-low-carbohydrate weight loss diet compared with an isocaloric low-fat diet after 12 mo. American Journal of Clinical Nutrition, 90, 23-32. doi:10.3945/ajcn.2008.27326
  9. Tay, J., Brinkworth, G. D., Noakes, M., Keogh, J., & Clifton, P. M. (2008). Metabolic effects of weight loss on a very-low-carbohydrate diet compared with an isocaloric high-carbohydrate diet in abdominally obese subjects. Journal of the American College of Cardiology, 51, 59-67. doi:10.1016/j.jacc.2007.08.050
  10. Halton, T. L., & Hu, F. B. (2004). The effects of high protein diets on thermogenesis, satiety and weight loss: A critical review. Journal of the American College of Nutrition, 23, 373-385.
  11. Nordmann, A. J., Nordmann, A., Briel, M., Keller, U., Yancy, W. S. Jr., Brehm, B. J., & Bucher H. C. (2006). Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: A meta-analysis of randomized controlled trials. Archives of Internal Medicine, 166, 285-293.
  12. Liebman, M. (2014). When and why carbohydrate restriction can be a viable option. Nutrition, 30, 748-754. doi:10.1016/j.nut.2013.11.021
  13. Merino, J., Kones, R., Ferré, R., Plana, N., Girona, J., Aragonés, G., Ibarretxe, D., Heras, M., & Masana, L. (2013). Negative effect of a low-carbohydrate, high-protein, high-fat diet on small peripheral artery reactivity in patients with increased cardiovascular risk. British Journal of Nutrition, 109, 1241-1247. doi:10.1017/S0007114512003091
  14. Cunningham, W., & Hyson, D. (2006). The skinny on high-protein, low-carbohydrate diets. Preventive Cardiology, 9, 166-171. doi:10.1111/j.1520-037X.2006.04853.x
  15. Te Morenga, L., Mallard, S., & Mann, J. (2012). Dietary sugars and body weight: Systematic review and meta-analyses of randomised controlled trials and cohort studies. BMJ, 346. doi:10.1136/bmj.e7492
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  17. Bidwell, A. J., Fairchild, T. J., Redmond, J., Wang, L., Keslacy, S., & Kanaley, J. A. (2014). Physical activity offsets the negative effects of a high-fructose diet. Medicine and Science in Sports and Exercise, 46, 2091-2098. doi:10.1249/MSS.0000000000000343
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