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Macronutrients: Purpose and Recommendations

Performance Training Personal Training

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The next in our series of posts developing a successful fat loss phase, builds upon what we have discovered in terms of why individuals ultimately fail in fat loss attempts (1), why there may be upper and lower limits on the amount of weight we may want to lose in one go (2), how long a fat loss phase can potentially last (3), as well as our last insight that looked at the role of calories and activity balance in maintaining a calorie deficit (4).

Today we begin to get into the individual roles that each macronutrient, namely Protein, Carbohydrates and Fats, play in a fat loss phase, as well as how we can start to establish our personal needs for each.

We begin with protein, as we know from previous posts, protein composes the vast majority of what our muscles are fundamentally made of. Therefore consuming enough protein across the day is critical in maintaining muscle mass during a fat loss phase. Our bodies simply don’t value skeletal muscle high in priority when it comes to further energy usage. It will always preferentially feed energy resources (even muscle protein itself) to more important elements such as the brain, heart, liver when resources are short.

Therefore the risk of muscle loss on a weight loss diet is a very real concern. As we keep saying, high levels of muscle mass are a luxury product.

However we also know that losing muscle mass to a high degree degrades our health, reduces strength, decreases mobility and limits our capacity for performance. Our goal within a fat loss phase is to loose NON ESSENTIAL TISSUE. Muscle mass is certainly essential. 

Most individuals when wanting to loose fat desire a more athletic, toned appearance. Losing large amounts of muscle creates a look that most individuals ironically don’t want. Shapeless and thin vs athletic and fit…

By taking in a sufficient amount of protein on a day-to-day basis, we create a resistance towards muscle loss by ensuring we have sufficient levels of the resources needed (amino acids) to support sustained muscle growth and recovery. 

Concurrent Resistance Training during a fat loss phase by definition enhances the retention of muscle mass. Alongside sufficient protein intake, resistance training provides the stimulus needed for repair and growth of new and existing tissue. A fat loss phase without simultaneous resistance training is likely to lead to an increase in the loss of muscle tissue due to lack of stimulus for muscle retention.

Alongside all these factors, protein intake reduces hunger. Anyone who has ate a large amount of protein in one meal (Viva Brazil anyone?) will have likely experienced that uncomfortable level of fulfilment that comes with high protein intake. This can be used to our advantage during a fat loss phase when we know that hunger is going to be a possible issue. Spreading out our protein intake and taking advantage of whole food sources can be a valuable tool in offsetting hunger.

When it comes to selecting our protein needs we have to consider, as always, whether upper and lower limits exist for daily ranges of intake.

At the lowest levels (below 0.5g per lbs of bodyweight) we are in the realms of protein malnutrition. This can occur intentionally through extended periods of deliberate fasting or with individuals suffering from disordered eating patterns. Or unintentionally, through a lack of protein consumption within the realms of an otherwise normal diet. Without choosing to list out the signs and symptoms, protein deficiency is not something we want to actively encourage.

Moving outside the realms of medical concern, the recommended daily reference intake via the NHS is a flat amount of 50g per day. Hopefully we can all see how flawed this is… 

A 120lbs female and a 220lbs male are both recommended to consume the same amount, in spite of both having vastly different levels of muscle mass…

Back in the realms of individualised figures with actual value above just preventing malnutrition, between 0.75 and 1g per lbs of bodyweight is likely to be the starting requirement for most individuals. 

Using our two examples above, that would be 90-120g for our 120lbs female and 165-220g for our 220lbs male. To put this into context, a typical 180g skinless breast of Chicken contains approximately 55g of protein in a single serving. For most individuals this is readily achievable on a day-to-day basis.

When we start to factor in regular activity and resistance training, the requirement for protein to support muscular recovery and new tissue growth may require an intake between 1g and 1.5g per lbs of bodyweight. This is likely to be the upper limit of protein intake for most, if not all, individuals. 

Above 1.5g of protein per lbs bodyweight we encounter no real benefit, and may actually lose out on the potential benefits that could be gained from the calories coming from greater carbohydrate or fat intake that may offer additional benefits.

Think of protein intake very much as a Goldilocks U-shaped curve with our “golden number” being around 1g per lbs of bodyweight.

Our next macronutrient up for consideration is Fat. 

Whist often considered the biggest contributor to potential weight gain (fat makes you fat right…?), no single macronutrient is likely to make an individual gain weight just by it’s own consumption. The balance of whole calorie intake is the cause of weight gain and weight loss as we well know.

However essentials fats are a must for the body to consume as we ourselves cannot make them endogenously. Fats have a vital role in supporting the endocrine system by acting as precursors for hormone production (cholesterol as a precursor for testosterone production for example…). 

Fat intake does however come with some caveats. Fats are the most caloric macronutrient on a gram for gram basis, at 9kcal/g compared to protein and carbohydrates each containing 4kcal/g. They are also the most lipogenic macronutrient, in that they are easily transferred into stored fat by the simple fact there is no conversion really needed, they are simply broken down and stored as fat tissue. Therefore it can be easy to over consume calories on a gram by gram basis when high levels of fat are consumed.

When choosing fat intake, we again look within the literature for upper and lower limits for intake. In a similar manner to protein, this appears to be specific to the individual at the lower end. Some studies have taken total fat intake down as low as 5g per day and seen little overall disruption to hormonal function. However typical recommended levels of intake indicate that at levels below 0.3g per lbs of bodyweight have shown a lowering in the function of our Hypothalamic-Pituitary-Gonadal Axis, the key regulator of our sex drive and sex hormone production. 

At the upper limit, at amounts above 0.5g/lbs we encounter potentially the same issue as the overconsumption of protein during the day. We may be losing out on the benefits that other macronutrients can provide due without sufficient added effects.

Therefore a starting point of 0.4g/lbs is our beginning recommendation. At which point individuals may move between 0.3-0.5g/lbs depending on whether we would prefer to utilise the additional calories elsewhere (more carbohydrates to support training for example) or if a hormonal response indicated that more fats may be beneficial.

Our final macronutrient is carbohydrates, often referred to as the primary fuel for intense activity. The role that carbohydrates play extends out far beyond just the simple role of calorie burning for training energy. Without overcomplicating the situation, a few examples and descriptions are listed below.

  • Glycogen-mediated Recovery: the greater the intake of carbohydrates (up to a point…), results in more fuller stored of glycogen within the muscles for future use as a fuel source. Greater intake also results in a quicker refuelling time for increase recovery rates.
  • Glycogen-mediated Anabolism: high levels of glycogen storage within the muscle tissues themselves activates the pathways for muscle growth. When glycogen levels are low, the body reduces these pathways and muscle breakdown pathways activate. 
  • Insulin-mediated Anabolism: with intake of carbohydrates, the hormone Insulin is released to assist in the re-uptake of glucose into the muscles and liver. Insulin is both anabolic (building of tissues) and incredibly anti-catabolic (prevents breakdown of tissues). Consistent carbohydrate intake over time increases the time in which Insulin in present (area under the curve)
  • Insulin-mediated Recovery: in anabolic effect of Insulin secretion assists in restoring glycogen levels within the muscles themselves, therefore increasing the speed of recovery.
  • Anti-Catabolic Effects to Support Muscle Tissue: the body will preferentially choose to use carbohydrates as its preferred fuel source even in the presence of other macronutrients. Carbohydrate intake quite literally acts as a sparer of muscle protein.
  • Anti-Catabolic Effects due to Cortisol Level Lowering: during periods of stress, the chemical Cortisol is released within the body as part of our stress response. Carbohydrate intake directly reduces the secretion of Cortisol (high sugar food intake when stressed…).
  • Reduction in Fatigue due to Cortisol Level Lowering: high levels of stress are fatiguing both mentally and physically, with carbohydrates decreasing Cortisol secretion, we also see a reduction in fatigue through greater carbohydrate intake.
  • Carbohydrates are Filling: on a gram per gram basis, you can eat a greater volume of food from carbohydrate intake (4kcal/g) than you can from fats (9kcal/g). If we want to give an individual more food (whilst maintaining calorie amounts), carbohydrates are much more effect source.

Selecting carbohydrate intake levels has a two-fold approach depending on the preference of an individual. Assuming that weekly calorie average intake remains stable, we can simply set a protein target intake (1g/lbs) and set a fat intake (0.4g/lbs) and use our remaining calorie amount to be set aside as carbohydrate intake.

As a simple example with a 2000kcal target intake in a 150lbs female;

  • Protein at 1g/lbs = 150g Protein = (4kcal/g) = 150*4 = 600kcals
  • Fat at 0.4g/lbs = 60g Fat = (9kcal/g) = 60*9 = 540kcals
  • 2000kcal – (600kcal + 540kcal) = 860kcal of Carbohydrates
  • 860/(4kcal/g) = 215g Carbohydrates

So our starting macronutrient recommendations on a day-to-day basis (*always subject to personalisation), would be 150g of Protein, 60g of Fat and 215g of Carbohydrates for a total intake of 2000kcal per day for this individual.

We also have the capacity to scale our carbohydrate intake based off work effort on a day-to-basis to provide an individual with more fuel on days in which they are more active and less on days they’re more sedentary.

Using our same individual, if she takes part in two hard training sessions and one moderate training session per week, we may adjust carbohydrate intake to accommodate.

Using our daily target of 215g, totalling 1505g per week, we can distribute as follows…

Monday: 300-320g of Carbohydrates – Hard Training Session

Tuesday: 150-160g of Carbohydrates

Wednesday: 240-260g of Carbohydrates – Moderate Training Session

Thursday: 150-160g of Carbohydrates

Friday: 150-160g of Carbohydrates

Saturday: 300-320g of Carbohydrates – Hard Training Session

Sunday: 150-160g of Carbohydrates

This would still equate to an approximate total of 1505g (215g x7) or 6020kcal across the week, we have simply shifted the amounts to match the variation in training intensity.

This is a strategy that does require consistency of behaviours in terms of food intake to prevent individuals taking in low-calories on high-intensity training days or simply loosing track of what has been taken in in relation to what type of session.

This provides us with a starting point for each macronutrient, however these are almost always further personalised to the individual. We can adapt within ranges to meet the requirements of the person. A client consuming a higher fat intake through a more mediterranean-type approach may benefit from reducing carbohydrates to some degree to allow for greater fat intake. Someone who is Vegetarian will like need to adapt the protein intake especially at the higher ends to make sure that food volume remains manageable over time. Whatever enables consistency and adherence over time, within reason, is the goal.

As we have discussed, each macronutrient has both an independent and inter-related impact on a fat loss phase. There are upper and lower limits to each that may support the outcomes we desire. By choosing to over consume a single macronutrient, we run the potential risk of the associated benefits found from adequate intake of others. 

Our takeaways from todays insight:

  1. Protein is the building block of muscle tissue. Even in a fat loss phase, the preservation of muscle is key. Consuming below 0.5g/lbs is likely to encounter medical concerns. Between 0.75-1g/lbs bodyweight is likely to be sufficient for most individuals. 1g/lbs is more appropriate for individuals taking part in resistance training. Above 1.5g/lbs offers no real benefit and may take away from the ability to consume sufficient levels of fat and carbohydrates.
  2. Consumption of essential fats is vital as we cannot create these fats endogenously. Essential fat intake also supports our endocrine system and hormonal functioning. Consuming below 0.3g/lbs in likely to cause some degree of hormonal disruption (loss of sex drive…). Consuming above 0.5g/kcal is likely to take away from the benefits we would get from re-assigning these calories to other macronutrients. Between 0.3-0.5g/lbs, scalable depending on preference and hormonal response with a starting point of 0.4g/lbs is a solid first option.
  3. Carbohydrate consumption has multiple anabolic and recovery-mediated benefits. We can either split carbohydrate intake evenly across the week using the calories remaining once protein and fat targets have been established, or we can distribute calories based on the level of daily activity to provide greater intake on days in which greater levels are needed and reducing carbohydrate amounts on days in which activity is lower. Light or “off” days at 1g/lbs, moderate activity days at 1.5g/lbs and 2g+/lbs on high activity days.

In our next insight we will take a further look at nutrient timing and how we can spread food intake across periods of time to assist in preventing the barriers we know to long term sustainability and adherence within a fat loss phase.

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