The Fitness Zone

The Importance of Proper Nutrition for Fitness and Weight Loss

Jan 05, 2024 | by Lacey Blackman

We’ve all heard the expression that you “can’t out-train a bad diet”. Regardless of how hard or frequently we exercise, proper nutrition will always serve as the cornerstone for achieving fitness and body composition-related goals. 

But what is considered ‘proper nutrition’? Where do we even start? With the internet, social media, and magazines saturated with varying, conflicting, and often biased information about diets and nutrition, it can be difficult to ascertain what approaches or practices are reliable, evidence-backed, and ultimately sustainable for long-term results. 

As daunting and challenging as it can be to make any degree of dietary change, it certainly doesn’t have to be overwhelmingly complicated or sacrificial to culinary enjoyment. After all, no singular food is inherently bad for us – however let’s explore how we can ‘have our cake and eat it, too’ by simplifying proper nutrition principles and how they can facilitate fitness and weight (fat) loss goals, as well as promoting overall health, wellbeing and a positive relationship with food.

Energy Balance

The first law of thermodynamics dictates that while energy cannot be created or destroyed, it can be converted from one form to another [1]. This means that if we want a shift in body composition to occur – whether that be weight gain or weight loss – there needs to be a disruption in energy balance. 

A simple way of illustrating how energy balance works is using the ‘calories in versus calories out’ concept whereby gaining weight requires eating in a calorie surplus and losing weight requires eating in a calorie deficit. The latter is preferably combined with exercise to both increase the energy deficit and support the retention of lean body mass.

A great first step to take in ensuring sufficient and sustainable nutrition intake that aligns with any fitness or weight loss goal is determining daily caloric needs. To do this, we recommend utilising the Eat For Health Program – a Government-endorsed incentive that provides basic healthy eating information and advice based on the latest scientific evidence and describes the best approach to eating for a long and healthy life [2]. Provided on this website are educational resources such as the Australian Dietary Guidelines and nutrition calculators to help shape healthy eating habits and determine baseline dietary recommendations.


Sometimes determining our daily caloric intake alone isn’t sufficient in facilitating our fitness and body composition goals. For example, 2000 calories a day worth of discretionary foods isn’t going to contribute to long-term sustainable results in comparison to a balanced diet consisting of all of the five food groups. Having a fundamental understanding of what food is made up of can help in making optimal dietary choices that support your goals and enhance well-being and longevity.

Food is made up of three primary macronutrients – carbohydrates, protein, and fats. There is a fourth macronutrient – alcohol – however as this provides no nutritional benefit, we will omit discussing this. Let’s explore each macronutrient in more detail and the importance of incorporating it into a balanced diet.


Carbohydrates are the body’s preferred and most efficient energy source. When ingested, carbohydrates are broken down into glucose – a simple sugar – which is readily used for energy production by cells throughout the body including the brain, muscles, and other tissues. 

Carbohydrates help fuel various metabolic processes and contribute towards energy needed to sustain physical activity and enhance exercise performance. When an adequate amount is consumed, carbohydrates spare protein from being used as an energy source, meaning that the body is less likely to break down muscle tissue for energy thus preserving lean muscle mass.

Not only crucial from an energy perspective, but carbohydrates play a vital role in digestive health and blood sugar regulation. Dietary fibre – a type of complex carbohydrate found in plant-based foods – supports a healthy gut microbiome and helps maintain regularity in bowel movements. Complex carbohydrates such as those found in whole grains, legumes, and vegetables can help regulate and control blood sugar levels as these foods are digested more slowly.

Carbohydrates aren’t “evil” as often portrayed in diet culture, however, it is worth knowing that not all carbohydrates are nutritionally created equal. While ‘simple’ carbohydrates can naturally occur in foods such as milk, other common forms such as raw sugar, corn syrup, fructose, and fruit juice concentrate are often added to highly processed foods such as soft drinks, cakes, biscuits, ice-cream, lollies, and cereals. As these types of discretionary foods offer little nutritional value and are often higher in calories, it is recommended to limit intake as much as possible to help reduce the risk of diet-related conditions and chronic diseases such as high cholesterol, high blood pressure, type 2 diabetes, cardiovascular disease, and obesity.

For these reasons, the consumption of ‘complex’ carbohydrates is encouraged due to being more nutritionally dense with vitamins, minerals, and fibre. Aim to incorporate a broad range of fruits and vegetables into your daily diet, as well as other sources such as nuts, beans, and whole grains.


Despite this macronutrient having been associated with negative health connotations in the past, research shows that certain dietary fats offer numerous health benefits in terms of providing the body with energy, protecting and insulating organs, supporting cell growth, maintaining good cholesterol levels and blood pressure, and helping the body absorb vital nutrients [3]. Some fats are even considered “essential” – such as Omega-3 and Omega-6 fatty acids – because the body cannot produce them on its own. And let’s be honest, fats add flavour and richness to foods – very important for making meals more enjoyable and satiating!

There are different types of fats and similar to carbohydrates, not all of them are created equal. The four categories of dietary fats are saturated, trans, monounsaturated, and polyunsaturated. Saturated and trans fats have been associated with increasing the risk of diet-related conditions and chronic diseases, however, unsaturated fats are considered to have the opposite effect in promoting good health and functionality.

When it comes to overall fat intake for a healthy diet, moderation is key. Try swapping out fried and processed foods that are higher in saturated and trans fats with quality unsaturated alternatives. For example, use avocados or nut butter as a spread in place of margarine or butter, snack on nuts and seeds instead of potato chips, use olive oil for cooking or as a salad dressing, and incorporate more fatty fish such as salmon or select leaner cuts of meat.


While all three macronutrients are crucial in supporting a healthy body, protein is arguably the most important of all! Protein consists of essential amino acids that are considered the “building blocks” of the body and are involved in various vital functions such as enzyme function, hormone production, immune system and structural support, and transport and storage of important molecules (like oxygen and lipids) throughout the body.

In the context of fitness and body composition goals, protein is responsible for muscle growth and repair, serves as an energy source (in the absence of carbohydrates and fats), and is a very useful weight management and appetite regulation tool due to being highly satiating.

The recommended daily protein intake will vary based on several factors such as age, sex, activity levels, and individual fitness or health goals. As a starting point, the Eat For Health Program suggests the following protein intake volumes for adults:

AgeRecommended Daily Intake
19-30 yr64 g/day (0.84 g/kg)
31-50 yr64 g/day (0.84 g/kg)
51-70 yr64 g/day (0.84 g/kg)
>70 yr81 g/day (1.07 g/kg)
19-30 yr46 g/day (0.75 g/kg)
31-50 yr46 g/day (0.75 g/kg)
51-70 yr46 g/day (0.75 g/kg)
>70 yr57 g/day (0.94g/kg)

[4] Eat For Health Program Nutrient Reference Values: Protein Recommendations for Adults

Bear in mind that the above suggestions are based on the Eat For Health Program recommendations and that these values are based on the shortest and least active person in each demographic group. For active and athletic populations, the recommended daily intake of protein is much higher and the International Olympic Committee consensus statement [5] recommends that a daily dose between 1.6-2.2 g/kg/day is optimal for strength-trained athletes whereas 1 g/kg/day for active persons and between 1.3-1.8 g/kg/day for non-strength-trained athletes is suggested.

Protein can be obtained from both animal and plant-based sources, and typically foods from this group provide a wide variety of important nutrients such as iodine, iron, zinc, and B12. There are six categories of protein-rich foods, which are lean meats, poultry, fish and seafood, eggs, nuts and seeds, and legumes and beans. Just be mindful that some smoked, salted, and preserved versions of these foods such as bacon, ham, and salami can be higher in saturated fats and may increase the risk of diet-related conditions and chronic diseases, and thus are considered to be discretionary items.

How Much Do I Need?

So now you may be asking yourself how much of each macronutrient you should be consuming that is consistent with your daily caloric needs. To simplify this step, we suggest using the Eat For Health Program’s nutrition calculators to determine your average recommended number of servings per day from each of the five food groups. The below quick-reference table is from the Eat For Health Educator Guide [6] in which these serving recommendations consider both macronutrient and micronutrient needs. Please note that these recommendations are based on the least active person in each demographic group. To learn more about your individual ‘foundation diet’ needs and what is considered a serving or portion size from each food group, visit

Nutrient Timing

An influential factor around nutrition that is often seen in the promotion of diets is when to eat to optimise fitness performance and strategically achieve body composition results. While this is an evolving and complex concept often applied to athletic populations, it is not an essential component on a foundational level.

For the everyday gym-goer or person simply looking at improving their diet and lifestyle, it isn’t necessary to overcomplicate nutrition with specific meal frequencies to achieve realistic and sustainable results. It is encouraged to evenly space out meals and snacks over the course of the day to help maintain stable blood sugar levels and provide a steady source of energy, however regardless of meal timing frequencies or preferences, it is the consistency of overall caloric intake across a 24-hour period that is most detrimental in achieving body composition results.

When it comes to macronutrient manipulation, there is evidence to suggest that evenly spaced protein distribution throughout the day (for example, 20g protein per meal) augmented muscle growth and strength in resistance-trained individuals [7]. On the contrary, the aforementioned study does warn that the benefits of this practice are likely minimal – especially if overall daily protein and caloric intake is sufficient and in conjunction with a resistance training regime.

There are other benefits to even protein distribution besides its effect on muscle protein synthesis. As protein is more satiating in comparison to carbohydrates and fats, including a modest volume of protein with each meal can help regulate appetite by helping you feel fuller for longer and limit overeating, thus facilitating weight loss through reduced energy consumption [8].

If you are an advanced gym-goer or athlete, nutrient timing can have a significant impact on performance. There are phases of training or certain sporting events that may require specific nutrition protocols to help prepare for the activity (pre-workout), enhance and sustain performance (intra-workout), replenish energy stores, and promote recovery or growth (post-workout). We won’t go into these concepts in-depth, however, these phases of training usually consist of strategic intakes of carbohydrates, proteins, and electrolytes to support performance, energy levels, and recovery.


Supplements have a heavy presence in the fitness industry thanks to clever marketing often selling a “shortcut to success”. Although there are a minor few products that are scientifically proven to be effective in supporting health and fitness goals, the majority are – to be quite blunt – useless. If one’s diet is already sufficiently balanced with adequate energy intake and incorporates a broad range of whole foods rich in vitamins and minerals, then supplementation isn’t likely to offer a noticeable difference (unless you have a legitimate medical issue or deficiency where supplementation is required).

Save your money when it comes to fat burners, BCAA’s, and pre-workouts – not only do these products contain a cocktail of ineffective and sometimes unsafe and unregulated ingredients, but you can’t out-train a bad diet, remember? However if  you want to invest in supplementation that complements your sufficient diet, active lifestyle, and ongoing fitness or body composition goals, it is recommended to research the below nutrients or products to determine if they can be of benefit to you (but ensure to consult your GP first!)

  • Omega-3 fatty acids may improve cognitive processing and their anti-inflammatory effects may reduce muscle damage or enhance recovery from intense exercise. It is recommended to include whole food sources rather than fish oil supplements in the long term however 2g/day is suggested. [5]
  • Creatine monohydrate is a naturally occurring nutrient however increased doses of up to 20g/day for 5 days followed by 3-5g/day to increase and maintain levels may enhance adaptive response to exercise by way of increased lean mass or strength, reduce symptoms of muscular damage/DOMS from exercise, improve cognitive processing and enhance recovery time. [5]
  • Protein powder in my opinion is considered to be more of a substitute rather than a supplement, however, it offers similar benefits as consuming protein from whole foods. Having a serving of protein powder may be a quick, easy, convenient, and mess-free alternative to preparing and eating a meal from scratch. For example, a busy working professional with a family may find it more realistic to consume a protein shake post-workout as opposed to eating a bowl of chicken salad. When sourcing a protein powder, look for whey protein isolate or whey protein concentrate varieties as the protein content will be much higher (between 80-90%) and may contain less sugar and “filler” ingredients.

In summary, proper nutrition is fundamental for successfully achieving fitness and body composition goals. It provides the body with energy to sustain physical activity and nutrients to support vitality. 

Regardless of your personal nutritional philosophy or preferences, it’s important that whatever dietary changes you implement are sustainable in the long term and contribute positively to your health and fitness pursuits. Making rapid and radical changes to your diet can be short-lived due to being unrealistic or having severe impacts on physical health and psychological well-being, so endeavour to take ‘baby steps’ when making any modifications.

Always consult with a healthcare professional for more personalised guidance.


[1] Stewart, K. (2023). Laws of thermodynamics.

[2] Department of Health and Aged Care. (2023). About the Australian dietary guidelines. Australian Government.

[3] Harvard Health Publishing. (2021). Know the facts about fats.

[4] Department of Health and Aged Care. (2023). Nutrient Reference Values. Australian Government.

[5] Maughan, RJ., Burke, LM., Dvorak, J., Larson-Meyer, DE., Peeling, P., Phillips, SM., Rawson, ES., Walsh, NP., Garthe, I., Geyer, H., Meeusen, R., van Loon, LJC., Shirreffs, SM., Spriet, LL., Stuart., Vernec, A., Currel,l K., Ali, VM., Budgett, RG., Ljungqvist, A., Mountjoy, M., Pitsiladis, YP., Soligard, T., Erdener, U., Engebretsen, L. (2018). IOC consensus statement: dietary supplements and the high-performance athlete.

[6] Department of Health and Aged Care. (2023). Eat For Health Educator Guide. Australian Government.

[7] Longstrom, J. (2022). Evenly spaced out protein leads to greater gains!

[8] Paddon-Jones, D., Westman, E., Mattes, RD., Wolfe, RR., Astrup, A., Westerterp-Plantenga, M. (2008). Protein, weight management and satiety.

Lacey Blackman

Lacey Blackman

Online Coach
Lacey Blackman is an Educator for the Australian Institute of Fitness and a Personal Trainer with over 9 years of experience in the fitness industry. After graduating from AIF in 2014 with a Certificate IV in Fitness (Master Trainer Level 1), Lacey opened her personal training and online coaching business “Lean Like Lacey” which specialises in women’s health and fitness. In that time, Lacey has gained hands-on experience within various fitness facilities around Brisbane - from privately-owned studios to commercial gyms. Lacey’s passion for health and fitness has since expanded into nutrition and business, and subsequently undertook a Certificate in Applied Sports Nutrition and Diploma of Fitness to continue growing her knowledge in these areas. Using her professional knowledge as a Personal Trainer and AIF Educator, and personal experiences as a professional natural bodybuilder, Lacey is determined to inspire and empower future generations of PTs in the ongoing fight against SEDS.

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