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Nutrition for Personal Trainers by Dr Crionna Tobin

Too many Personal trainers give out “one-for-all” meal plans or nutrition programmes, regardless of the client’s goal. However, despite having several commonalities, a few crucial areas need to be addressed in order to maximise your results with clients.

The majority of clients seeking nutrition advice have one of two goals; weight loss or improved exercise performance. Although the temptation may be to redistribute “cookie-cutter” meal or nutrition plans regardless of client goals you may have more success if you personalise some of the advice and/or nutrition strategies you use with these all too different populations.  Below I have set out the key differences between clients and their goals.
1. Calories 
Calories are the most important factor for clients regardless of whether the goal is fat loss, performance or both. Often, calories are only considered for weight loss clients, while carbohydrates are the only consideration for performance-driven individuals. This, however, can be a critical mistake for an exercise performance client as fueling with the appropriate amount of calories for training and competition is crucial for performance, recovery and training adaptations.

Dietary carbohydrates provide an individual with the energy to train and compete at high intensities and are the most important fuel source for those seeking to improve performance. However, energy from other fuel sources (fat and protein) are also needed during exercise but on the premise that their energy requirements are met. For example, a 60 kg marathon runner focusing solely on increasing their carbohydrate intake to 10g per kg body weight for race day (10 x 60 = 600g carbohydrate),  which equates to 2,400 kcal (600g x 4 calories) and with their protein and fat calories amounting to 600 kcal, consumes a total of 3,000 kcal.

However, on race day, it is estimated that athletes burn approximately 2,800 kcal for the marathon alone, so their daily caloric requirement could be upwards of 4,000 calories! Despite having a very high carbohydrate intake this athlete has consumed less than 75% of their daily caloric requirement. Failure to eat enough calories to support training and daily living can lead to low energy levels, failure to recover appropriately, illness and even injury in the long term.  While focusing on carbohydrate is critical for athletes seeking performance benefits, the primary goal is to hit daily caloric targets and subsequently carbohydrate requirements.

On the other hand, when seeking weight loss, calories are also the primary focus and you should ensure that your client’s caloric intake is less than their caloric expenditure. However, “If It Fits Your Macro’s” (IIFYM) is currently a common strategy that focuses on tracking macronutrients. The diet is based on the foundation that once you hit your macronutrient targets the quality of food eaten is irrelevant.  Some clients find this a useful strategy as they feel there is more flexibility in their food choices, which helps them to better adhere to their diet. However, others choose lower quality foods that are tastier but which could over time lead to overeating due to their low protein and fibre content. How your client achieves a prolonged caloric deficit should be determined by what they will stick to, to achieve their goals. What we do know for certain is that to achieve weight loss, a calorie deficit is essential!

Figure 1

2. Macronutrients 
Once the calorie requirements of your client are determined, the focus then switches to the macronutrients composition of the diet. In truth, if fat loss is the sole aim of the programme, the macronutrient composition of the diet is largely irrelevant. Calories are the determining factor in weight control and once the calorie intake creates a calorie deficit the client will lose body fat, regardless of the type of food consumed. However, a diet high in protein will increase satiety, helping the client to stay fuller for longer, which may potentially help them to adhere to their diet. I recommend aiming for a protein intake of roughly 2g/kg/BW2, with the remaining calories made of carbohydrate and fat. Research has found that individuals eating highly processed foods high in sugar and fat are more likely to overeat, so it is important to also focus on the quality of foods consumed3. Micronutrients are also a consideration for health and a diet of highly processed foods are at risk of nutrient deficient and subsequent health issues.

Conversely, when it comes to sports performance, macronutrients are much more important. There has been a significant increase in athletes using high-fat diets, however, research suggests that when you are chasing performance, high fats diets are not the way to go. High-fat diets have been shown to reduce the running economy of an athlete, due to an increased oxygen consumption4. This means that the effort required to run at a given speed is increased! Carbohydrates, however, are utilised at higher intensities, so when athletes are looking to optimise performance they should focus on consuming a moderate to high carbohydrate diet of between 5-10g/kg/BW5. Further to this, an athlete needs to consume adequate protein. Athletes should also aim to consume 2g/kg/BW2 and this should be spread evenly through the day to maximise muscle protein synthesis, aiming for servings of 20-30 grams every 3 hours.
3. Supplements 
Supplement advice should be goal specific. For fat loss, there are no supplements that can support the process without a caloric deficit. However, there are some that may improve performance and subsequently increase expenditure, which will indirectly increase weight loss.
Supplements that support weight loss are those that support health as the healthier the client feels the more likely they are to exercise and continue on their weight loss journey. I always recommend Vitamin D to clients, particularly in the winter months. Adding whey protein to meals such as breakfast and or snacks can also be a convenient solution for those who struggle to hit their daily protein targets. **Sports performance supplements include Creatine, Caffeine, Beta-Alanine and Whey protein. Some of these supplements are better suited to certain sports than others and should be advised based on their application to that sport. For example, all of the aforementioned supplements are applicable to team sports, whereas beta-alanine may not be as applicable to endurance sports due to the intensity. Refer back to the supplementation module in the Optimum Nutrition for Health and Performance course for optimal doses, frequency and timing of each supplement. 

Figure 2

Figure 2: Illustrates the hierarchy of importance in relation to nutrition when it comes to fat loss and performance.
4. Weight loss and performance – can you get the best of both worlds?
So far, fat loss and sports performance clients have been separated but what if a client wants both? In truth, a calorie deficit is not optimal when looking to optimise performance but there are some steps that can be taken to get the best of both worlds:
Undulating calorie intake: this approach involves periodising an athlete’s calorie intake over a prolonged period. Calories in versus calories out is not a static model, meaning that you can look at total calories over a week or month. For example, a daily calorie target of 2,000 equates to 14,000 per week. This 14,000 calories can then be split up to what best suits the energy demands of an athlete on given days, swapping between a high-calorie intake for training days and lower calories on rest days, yet still hitting the weekly target of 14,000. The below table shows how an undulating caloric intake over a week period.

Monday (training day)   – 3,000
Tuesday (rest day)          – 1,250
Wednesday (rest day)    – 1,250
Thursday (training day) – 3,000 
Friday (rest day)          – 1,000
Saturday (game day)      – 3,500  
Sunday (rest day)            – 1,000  
Weekly Calorie Intake – 14,000  

Regardless of your client’s goal, a diet consisting largely of unprocessed and whole foods is optimal for both performance and fat loss. Once this is achieved, the above recommendations can be implemented in order to optimise your client’s results but it is also important to remember that you need to be dynamic in your approach and can adapt your strategy based on your client’s current needs and lifestyle in order to achieve their long-term goal!
NOTE: The following information is for educational purposes only and does not reflect the opinion of Glanbia Performance Nutrition, nor is it intended for product marketing purposes.
1. Loftin, M et al. 2007. Energy expenditure and influence of physiologic factors during marathon running. The Journal of Strength & Conditioning Research, 21(4), pp.1188-1191
2. Phillips, S.M. and Van Loon, L.J., 2011. Dietary protein for athletes: from requirements to optimum adaptation. Journal of sports sciences, 29(sup1), pp.S29-S38.
3. Hall, K.D et al. 2019. Ultra-processed diets cause excess calorie intake and weight gain: an inpatient randomized controlled trial of ad libitum food intake. Cell metabolism.
4. Burke, L.M et al. 2017. Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. 
5. Bussau, V.A. et al. 2002. Carbohydrate loading in human muscle: an improved 1 day protocol. European journal of applied physiology, 87(3), pp.290-295.