6 Week Cut- Part II- The Science

Last week my boyfriend Joel gave us an insight on to his experiences with a 6 week hard cut. He had no particular reason to cut, besides having a goal to work towards, and being able to push himself. If you haven’t read the article, check it out- 6 Week Cut- Part I . Below he goes into a little bit more science to explain his plan for the cut. If you keep tuned, he has a few more posts planned, so stay with us to keep tabs on his progress!

Determining Calorie Deficit

So we know that pretty much any form of calorie deficit will lead to weight loss. For the majority of individuals, losing fat whilst maintaining muscle will be the ideal goal. There’s better and worse ways to go about setting up this calorie deficit. Eating only cabbage soup alongside no exercise will certainly cause weight loss. But it will also result in muscle loss, as well as being unbelievably bland and unsustainable.

In order to have the most precision and control, my favourite technique for losing weight is to track calories and macronutrients (i.e. proportion of protein, carbohydrates and fats) using the phone app “myfitness pal”. It allows you to input exactly how much of each type of food you are eating (after you scan barcodes and weigh out ingredients/portions). So I can essentially figure out how much is going into my body and match this to how much is going out*. My maintenance calorie intake is around 2900-3000kcals.

*To determine/estimate your calorie expenditure (outgoings), firstly input your information into an online calorie calculator, such as here. Aim to eat approximately this amount of calories for 2 weeks. Weigh yourself daily. If your weekly weight average remains pretty much the same, then you can consider that as your maintenance calorie requirement.

According to some early research, each 1lb (0.45kg) of fat requires an energy deficit of around 3500 calories to lose (Thomas et al., 2014). Now whilst this number may not be 100% accurate, it gives us a good place to start. So theoretically speaking, if you create a 500 calorie deficit each day over a 7 day period, 1lb of fat should be lost.

My plan for this cut is to eat around 2100-2200 calories per week day, roughly giving me a 700-900 calorie deficit on those days. In order to improve my adherence (ability to stick to the diet), I have allocated myself one cheat day on the weekend, and one maintenance day on the weekend. With these measures in mind, I’m looking to lose around 1lb-1.5lbs of weight per week for 12 weeks.

Manipulating Macronutrients

The 3 main macronutrients we consume on a day to day basis are carbohydrates, protein and fats. These nutrients are considered macronutrients, because they are needed in large amounts (compared to micronutrients) and provide the body with energy. 1g of carbohydrate provides 4 calories, 1g of protein provides 4 calories and 1g of fat provides 9 calories. So a diet containing 300g of carbohydrates, 150g of protein and 80g of fat will provide approximately 2520 calories (300 x 4 = 1200 calories of carbs, 150 x 4 = 600 calories of protein, 80 x 9 = 720 calories of fat).

After setting a calorie deficit, protein intake is the second most important variable to control. Compared to the other macronutrients, protein has a number of benefits when it comes to dieting. These include improved muscle mass retention, higher satiation and a higher thermic effect (aka requires more calories to digest and absorb) (Noakes et al., 2005). For individuals involved in weight training, research has suggested that consuming protein in the region of 1.5-2g per kg of bodyweight (Aragon et al., 2017). During a calorie deficit, in lean, resistance training individuals increasing this to 2.3-3.1g per kg of bodyweight has been shown to improve muscle mass retention (Helms et al., 2014). Due to this reason, I will be aiming to consume between 166-207g of protein each day, equating to 664-828 calories.

Recently, it has become clear that when calories and protein intakes are matched, the proportion of carbohydrates to fat does not have a huge influence on fat loss (Hall et al., 2015). Therefore, personal preference should dictate the remaining breakdown. After trying a low carbohydrate in the past, I found that it left me extremely drained and unable to train as effectively in the gym. Because of this, I have opted to set my fat intake lower and carbohydrate intake higher. I will be aiming to consume around 235g of carbohydrates (940kcal) 50g of fat (450kcal) and 185g of protein (740kcals) = 2130kcals total.


To summarise part 1, after 3 years of bulking I have decided to cut. I will be tracking my calorie and macronutrient intakes using myfitnesspal. I will be in a 700-900 calorie deficit during weekdays, with more relaxed food intake on weekends. Over a 12 week period, I’m estimating a 5-7kg weight loss, with the majority being body fat.

The next part of this article will look into more detail at my exercise routine and how this ties in with dieting/muscle retention. I’ll also give a more detailed look into my daily diet, and how a flexible approach will allow me to stay happy and sane throughout. Finally, it will also cover my first 1-6 weeks worth of progress on the cut, including any setbacks, modifications and learning curves along the way.


Aragon, A. A., Schoenfeld, B. J., Wildman, R., Kleiner, S., VanDusseldorp, T., Taylor, L., … & Stout, J. R. (2017). International society of sports nutrition position stand: diets and body composition. Journal of the International Society of Sports Nutrition, 14(1), 16.

Hall, K. D., Bemis, T., Brychta, R., Chen, K. Y., Courville, A., Crayner, E. J., … & Miller, B. V. (2015). Calorie for calorie, dietary fat restriction results in more body fat loss than carbohydrate restriction in people with obesity. Cell metabolism, 22(3), 427-436.

Helms, E. R., Zinn, C., Rowlands, D. S., & Brown, S. R. (2014). A Systematic Review of Dietary Protein During Caloric Restriction in Resistance Trained Lean Athletes: A Case for Higher Intakes. International Journal of Sport Nutrition and Exercise Metabolism, 24, 127-138.

Noakes, M., Keogh, J. B., Foster, P. R., & Clifton, P. M. (2005). Effect of an energy-restricted, high-protein, low-fat diet relative to a conventional high-carbohydrate, low-fat diet on weight loss, body composition, nutritional status, and markers of cardiovascular health in obese women. The American journal of clinical nutrition, 81(6), 1298-1306.

Thomas, D. M., Martin, C. K., Redman, L. M., Heymsfield, S. B., Lettieri, S., Levine, J. A., … & Schoeller, D. A. (2014). Effect of dietary adherence on the body weight plateau: a mathematical model incorporating intermittent compliance with energy intake prescription. The American journal of clinical nutrition, 100(3), 787-795.

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