BACKED BY SCIENCE: Fat Loss for Athletes – Nutrition Periodisation

For many athletes across all levels and disciplines, the goal is to lose body fat. This is either for aesthetic or performance purposes in attempt to improve their role as an athlete within their given sport. Regardless of the reason, many wish to drop body fat and become leaner. Of which, countless athletes approach this goal incorrectly and experience decrements in their performance and various aspects of their health. Therefore, the aim of this article is to give an overview of the different areas of fat loss nutrition that needs to be acknowledged and implemented in order to successfully lose body fat without the expense of major performance losses and adverse health.

Some Fundamentals

Calorie restriction; the fundamental principle of fat loss nutrition is balancing energy intake and energy expenditure. With regards to this, three possible outcomes are likely to happen;
  • If energy intake equals energy expenditure, no changes in bodyweight will be observed.
  • If energy intake is greater than energy expenditure, weight gain will be observed.
  • If energy intake is less than energy expenditure, weight loss will be observed.
With the aim of losing body fat, positioning yourself with the latter will produce the most favourable outcome. In essence, the aim is to create a calorie deficit in order to drive fat loss. Achieving a calorie deficit can be obtained via two methods, decreasing calorie intake or increasing energy expenditure. For the athlete, further increasing energy expenditure may not be practical due to the already high levels of activity undertaken. In this case, further increasing energy expenditure through more activity and exercise may be detrimental to performance, recovery and the adaptive response to training. With this in mind, it would be pragmatic to pursue fat loss in the way of reducing dietary calorie intake and portion sizes. Therefore, ensuring this is made a high priority will guarantee fat loss success. However, it would be prudent to acknowledge that this is not as simple due to many interfering behavioural and social factors making a calorie restricted diet difficult to adhere to. Nonetheless, it’s simply a case of finding an approach and modifying behaviours appropriately. It’s worth noting that the intricacies of nutrition; nutrient quality, meal frequency, meal timing, supplements etc will not overcome a calorie deficit – If this is not the primary focus, then the dieting phase will end in failure. I feel that this needs reiterating as this; the most important aspect of fat loss nutrition becomes much overlooked.

Athlete vs Non-Athlete: The low carb Vs low fat debate

It’s been well established in the literature that a calorie restricted diet is needed for fat loss. However, much debate on macronutrient ratios still exist with regard to an optimal approach. Henceforth, the low carb vs low fat debate continues. For the non-athlete, macronutrient ratios play a small role in rates of fat loss and neither approach appears to be significantly superior when the body of evidence is reviewed. It is commonly believed that the carbohydrate-insulin model of obesity holds true where high carbohydrate diets irrespective of calorie intake cause obesity and hinder fat loss. This is primarily through high carbohydrate diets being fattening via increased insulin secretion. In return, this increases the partitioning of energy towards fat tissue as opposed to being used as fuel to more metabolically active tissues, such as muscles and vital organs. Despite logical reasoning, this theory fails to be true during experimental trials (Hall et al, 2017). In an extensive review by Wu et al (2013), it was concluded that different types of diet, with a similar time frame and calorie restriction only differed by 1-2kg. This body fat loss did not reach clinical significance and would be a disappointing amount to lose in the real world. Therefore it is suggested that personal preference should dictate what macronutrient should be dominant after protein intake has been set. Therefore, greater macronutrient flexibility is allowed for the non-athlete. In other words, if you like to eat more carbohydrates or you like eat more fat – This does not matter assuming that you consume adequate amounts of protein and that you are deficient in calories.
For the athlete counterpart, these guidelines become far more rigid to ensure exercise performance is maintained. In this instance, it would be wise to advocate a higher carbohydrate and lower fat approach. In essence, within the daily calorie budget, carbohydrates will offer a more favourable outcome as opposed to dietary fat for athletes wanting to perform at higher levels. Furthermore, higher carbohydrate diets at the expense of reducing dietary fat appears to be more advantageous for retaining lean body mass during periods of calorie restriction in athletes (Garthe et al, 2011; Maestu et al, 2010; Walberg et al, 1988). It has therefore been termed that high carbohydrate diets become ‘protein sparing’ during periods of energy restriction. For the athlete looking to lose body fat, retaining lean body mass and sustaining exercise performance should be a very high priority.

Some Performance

One on the most received messages as an athlete is to consume carbohydrates, pre, during and post exercise to aid with adequate fueling, support athletic performance and optimise rates of recovery. Carbohydrate provision and its role in enhancing exercise performance are well documented, where carbohydrate availability through glycogen stores and diet is a key indicator for sustaining prolonged exercise performance. In this instance, carbohydrates are still considered to be ‘king’ and the most important nutrient for optimising athletic performance. This is primarily through maintaining muscle and liver glycogen stores which become compromised during the latter phases of exercise – however is dependent on the type, intensity and duration of the exercise session or event. Knowing this, there should be little dispute with regards to macronutrient ratios within a calorie restricted diet for athletes. Therefore, an athlete would adopt a higher carbohydrate and lower fat approach. In terms of the continued fat for fuel debate that is always topical amongst endurance athletes, a more extensive review on the issue can be found HERE.

Some Budgeting

If you ask any strength and conditioning coach, they’ll most likely periodise their training into; high, medium and low demanding days. Therefore, we need to adopt and apply the same approach through calorie periodisation. Calorie periodisation is otherwise known as calorie budgeting. In my opinion, this is a great method for fat loss whilst being able to sustain exercise performance. When it comes to calorie budgeting, it encompasses the daily tasks and how you opt to meet them. You have two options here; will you spend your calories wisely, or poorly? Since carbohydrates drive exercise performance, opting for a different carbohydrate intake on different training days would be advisable in order to fuel the work required. Therefore, undulating carbohydrates will ensure adequate fuelling, sustaining exercise performance and recovery.
For example, If you had different training demands throughout the week, categorised into; high, medium and low days, but choose to eat the same amount of carbohydrates every day – some days would result in under-fueling and under-recovery, where some days would be the opposite. As calorie intake can’t be infinite due to body composition goals and health, forward planning for the week ahead would be favourable to ensure full use of your calorie allowance. Henceforth, undulating your carbohydrates would be a wise way of doing so. I.e. meet the body’s demands and fuelling the work required. Practically speaking, many athletes will compete on the weekend. Since lower calorie and carbohydrate approaches impair exercise performance, you would not opt to restrict your intake on the days you wish to perform or carbohydrate load. For body composition purposes, the fat loss phase and calorie restriction would run from Monday to Friday, where calories will be restored in preparation for the weekend’s performance. In essence, you’ll adopt a five day fat loss diet. As fuelling and recovery demands require high calorie intakes, a more aggressive calorie restriction will be required during the week to compensate. In part, performance gains during the week may become slightly impaired; however this will be at the expense of being able to perform at a high level on the weekend. I would suggest doing it this way if body composition goals are a very high priority. Wouldn’t you agree that it’s perhaps better to have a poor(er) training performance, as opposed to a poor competition performance? I believe that this is a compromise and tradeoff worth considering. To ensure competition performance doesn’t deteriorate, carbohydrate loading to a certain extent 24-36 hours prior to the event would be encouraged for complete repletion of muscle and liver glycogen stores as a good assumption can be made that levels will be much lower due to the nature of calorie restricted diets and higher  training volumes. Finally, the extent of the carbohydrate load will be dictated by the nature of the event competing in and as mentioned, the carbohydrate status going into the carbohydrate load.

Some Protein

As previously mentioned, higher protein diets are more favourable in retaining lean body mass in athletes undergoing a fat loss phase. In addition to this, evidence suggests that lean body mass can not only be maintained, but increased under periods of heavy calorie restriction and intensive exercise. Longland et al (2016) investigated the different outcomes of a low protein diet (1.2g/kg/bw) vs a high protein diet (2.4g/kg/bw) during a six session per week, four week training block where 40% of the calories were deducted from maintenance. Interestingly, 1.2kg of lean body mass was gained in the high protein group, where the low protein group unexpectedly maintaining lean mass. This is surprising as the lower protein intake is deemed to be ‘too low’ to support muscle mass maintenance. Furthermore, higher rates of fat loss were observed in the high protein intake compared to the lower protein intake; 4.8kg and 3.5kg respectively. In this instance, further increasing protein is beneficial for both increasing lean body mass and decreasing fat mass when calorie intake is severely restricted.
Following on from this, Anonio et al (2015) investigated whether an even higher protein intake was superior. Over an 8 week period, forty eight trained participants trained five times per week and consumed either a high protein diet (2.3g/kg/bw) or a very high protein diet (3.4g/kg/bw). At the end of the eight weeks, both groups gained 1.5kg of lean mass suggesting, and in agreements with previous literature that more protein does not equate to better gains with regards to proteins ability to build muscle. That being said, a very high protein intake does appear to be superior with losses in fat mass where participants lost 1.6kg compared to 0.3kg. Reasons being are still unclear, however it is theorised that it’s due to proteins higher thermic effect. It’s worth noting that very high protein intakes will displace dietary carbohydrates and fat, which could negatively impact performance and health over a long period of time.
For an in depth review on how to optimise protein intake to build muscle, lose fat and become stronger – check out my free downloadable resource below.

Some Rates of Fat Loss

During periods of energy restriction, compromises and tradeoffs will always exist. In most cases, the greater the duration and intensity of the fat loss phase further exacerbating these issues. Most specifically, compromises are seen in lean body mass retention, recovery, fueling, immune function, injury rehabilitation, cognitive function and wellbeing. Since the level of energy deficit controls this outcome, rates of weight loss can be prescribed in order to dampen these effects. Therefore, it has been suggested (Helms et al, 2014) that rates of fat loss in already lean individuals should be gradual with the aim of 0.5kg loss per week. During the initial weeks of a dieting phase, rates of weight loss may be higher due to losses in body water, glycogen, food bulk etc. Therefore this initial 1-2 week period of elevated rates of weight loss may mask the true rates of fat loss. Using these guidelines, realistic and safe goals can be set if bodyweight goals are a concern, i.e. weight making sports. If rates of weight loss beyond this are required to meet a deadline, then these compromises will become more apparent. It’s worth noting that these guidelines are mostly for long term periods of weight reduction where very short terms periods can be more aggressive and go beyond these rates of fat loss; approximately 1kg per loss per week if the window is closing. For example, the participants in the Lanland et al (2016) study lost on average 1.2kg per week and were still able to gain muscle. For individuals starting with much higher body fat mass, rates of weight loss can be further increased compared to their already lean athlete counterparts as these compromises won’t be as robust. For a more in depth review examining the consequences of becoming lean by following heavy energy restricted diets, I would encourage you to read HERE.

Some Adaptation

Fat loss is never linear. Unfortunately, you can’t simply induce a 500kcal deficit per day and continually to lose body fat. A process known as adaptive thermogenesis occurs in response to reduced energy availability (EA). Since there is less energy coming in and stored energy lowers, metabolic rate, i.e. the amount of energy that you expend will reduce. In this sense, rates of fat loss will decline until a plateau occurs. This is a normal component of fat loss, it will happen to everyone, it isn’t a case of; will it happen, it’s more of a case of when will it happen? Therefore, it’s very important to understand the ‘why’ and through what component of metabolism this effects in order to preempt and put strategies in place to overcome this decline in progress. This in part, has a large impact on the amount of energy we expend and is referred to as Total Energy Expenditure (TEE). TEE plays a large role during a fat loss phase, and can be divided into four categories;
  • Basal Metabolic Rate (BMR) – the energy required to run cellular processes within the body.
  • Thermic Effect of Food (TEF) – the energy required to break down and process foods eaten.
  • Thermic Effect of Exercise (TEE) – the energy burnt through exercise
  • Non-Exercise Activity Thermogenesis (NEAT) – the energy burn through movement that is not classified as ‘exercise’.

During periods of calorie restriction, TEE becomes reduced to compensate for the lack of energy provision. This is an uncontrollable adaptive process of dieting and occurs through the reductions in BMR and NEAT components of TEE. BMR reduces via two uncontrollable means; 1) calorie restriction to facilitate weight loss (adaptive thermogenesis), 2) being a smaller person (small individuals require less calories). The component of BMR that we can control is NEAT. Since NEAT is essentially energy expenditure through movement such as walking and fidgeting , this becomes reduced to preserve energy stores. In other words; subconscious laziness. This is sometimes a sufficient compensation to reduce or eliminate the balance of energy intake and energy expenditure. Picture this;
  • To lose body fat, you remove 300kcal from food to become deficient in energy.
  • This reduction in calorie intake causes you to become subconsciously less active and you move about less. Let’s say that this decrease in expenditure is 300kcal.
  • The calorie deficit would equal zero.  The subconscious laziness has over-ridden the calorie deficit induced by food and you’re back to square one.
Again, this is over simplified, but being mindful of the fact that this will happen can be used as a strategy to offset this compensatory mechanism. This is where measuring movement through activity trackers can be very beneficial as it can highlight the level of laziness and change behaviours to ensure that you maintain the same level of energy expenditure outside of the gym. Anecdotally, this is where you’ll see bodybuilders during a competition preparation phase increase the amount of cardio they do on a weekly basis – unknowingly, they are doing it to offset metabolic adaptations to weight loss as they have perhaps become increasingly sedentary outside of the gym.

Some Closing Thoughts

The concept of fat loss is very straightforward as it’s simply the balance between the amounts of energy consumed via food against the amount of energy expended through activity. However, this concept often become overlooked where athletes will miss the bigger picture and place a lot of time and energy focusing on the finer details that yield very small results. Aspects of diets such as meal timing, macronutrient distributions and even supplements do play a role for fat loss, but will have very poor outcomes unless calorie intake and portion control is revised first. For the office worker who casually trains and wishes to lose weight, placing efforts on calorie and protein intake whilst improving eating habits will yield great results. For the athlete, far more rigidity exists with regards to macronutrient ratios, meal timing and daily/weekly budgeting of calories. If this isn’t considered, then decrements in performance, lean body mass retention and health may become probable.
One of the main reasons why fat loss diets fail is because they are difficult and uncomfortable, as is any form of restriction in our lives. If fat loss goals are achieved through a dieting phase, rarely are they maintained long term. This is why sustainability and longevity of the approach is very important for the individual and personal preference; scheduling and personal beliefs must be accounted for. By all means, dieting is tough; however the goal would be to make it a little less tough and somewhat more enjoyable for long term success. Furthermore, becoming educated in the process will play a factor in adherence as you’ll simply know what’s coming – therefore can mentally be prepared for it. Many athletes or general population don’t know why they’re finding something difficult and are unaware of what the next step is, so they default back to normal eating habits because it’s much easier and more comfortable. Finally, many individuals believe that they must adhere to this lowered calorie intake for the rest of time to maintain their new found bodyweight where this at most is not true. In the grand scheme, fat loss phases are a short term process, a short term restriction. Once fat loss goals have been achieved, calorie intake and portion sizes can return to maintenance to maintain bodyweight. Albeit, still lower than they’re previous maintenance intake; smaller people simply need less calories.


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