Body Fat, Lean Mass and Waist Circumference Changes After Six Weeks Using Nutrient Optimiser

Most people think they want to lose weight. But what they really want is to lose fat and build muscle.  

While it’s nice to look good naked, keeping your body fat low and muscle mass high is central to managing diabetes and a plethora of metabolic diseases.

While the first Nutrient Optimiser Challenge was set up to look like a weight loss competition, the meal plans and optimised foods and meals were created to enable users to maximise fat loss while minimising loss of lean body mass (LBM) using high satiety, nutrient-dense meals that contain adequate protein.


Your waist to height ratio is an excellent marker of metabolic health, with a waist to height ratio of 0.5 aligning with the best odds for longevity.  

The chart below shows the reduction in waist circumference during the challenge, with an average loss of around 6.5% over six weeks.

Rate of fat loss

Most participants tracked their body fat on a daily basis using bioimpedance scales. On average, participants reduced their body fat at a rate of 1.8% per week during the challenge (i.e. change in body fat/starting body fat). The average change in body fat for men was 2.1% per week and 1.6% per week for women.

Rate of lean body mass gain

Tracking weight alone can be discouraging.  It is much more useful to track lean mass and body fat separately. The holy grail is ‘re-composition’ where we see body fat go down and lean mass increase. The chart below shows that most people gained a significant amount of lean mass during the challenge.

The growth in lean mass was greater in women than men.  This could be because many of the women were starting from a relatively low protein intake with lower levels of lean body mass. Hence, they responded with quick growth in lean body mass, even without adding resistance exercise.

Lean body mass vs fat mass change

Whether you are going to lose or gain lean mass during weight loss depends on a lot of things including:

  • nutrition (mainly protein),
  • resistance training,
  • hormonal status (e.g. testosterone levels),
  • sleep and stress,
  • baseline protein intake, and
  • how much lean mass you start out with.

While there is some noise/scatter in the short term, we can still monitor and manage the long term trend.  The Nutrient Optimiser Smart Macros algorithm recommends an increase in protein intake where a user is losing more lean body mass than fat mass.


The chart below shows the rate of fat loss and lean body mass for Jason who started the challenge at 238 lbs (108kg) and 24% body fat.  


The chart below shows the rate of body fat and lean mass change for Diane who started the challenge at 157 lbs (71 kg) and 34% body fat.

Protein can be even more important for lean people

People with more fat to lose are more likely to find it easier to maintain their lean mass and lose fat.  Focusing on high satiety meals will provide plenty of protein to enable them to retain muscle during fat loss. The body can easily meet their energy requirements from their stored body fat without needing to tap into their lean mass.

In contrast, leaner people will need to be careful to eat enough protein and not lose weight too quickly in order to ensure that they don’t lose excessive levels of lean mass.   As shown in the chart below from a review paper by Stuart Phillips, muscle mass is best preserved when we have higher levels of protein, particularly if you are targeting an aggressive deficit and working out.  

If you are targeting a moderate energy deficit then a minimum protein intake of around 1.4 g/kg BW may be adequate.  However, if you are targeting a very aggressive energy deficit then higher levels (up to 2.6g/kg BW) will be beneficial to prevent loss of lean mass.  

If you are active and undertaking resistance training you will also need more protein to maintain lean mass. Eric Helm’s Master’s Thesis found that bodybuilders undergoing significant calorie restriction need to consume up to 3.1 g/kg LBM to maximise preservation of lean muscle.  

Practically though, it can be quite hard to find foods that will provide enough protein in a large calorie deficit.  For people who are looking for a more casual and long term sustainable weight loss, the Nutrient Optimiser will highlight foods and meals that will tend to provide adequate protein, nutrients with high levels of satiety.  

However, if you are preparing for a bodybuilding competition or are serious about driving a rapid change in your body composition, the Smart Macros algorithm will help you dial in your protein, fat and carb ranges to achieve your goals.  

How Can I Calculate My Nutrient Intake?

If you’re interested in checking if you’re getting just enough dietary phosphorus, you can check your nutrient profile using our Free 7-Day Nutrient Clarity Challenge

After a week of tracking your current diet in CronometerNutrient Optimiser will give you a prioritised list of foods and NutriBooster recipes that will help you plug your current nutritional gaps.

Level Up Your Nutrient Density

To help you level up your nutrient density, we’ve prepared a Nutritional Optimisation Starter Pack to ensure you are getting plenty of all the essential nutrients from the food you eat every day.    

The free starter pack includes:

  • Maximum Nutrient Density Food List
  • Sample Maximum Nutrient Density Recipe Book
  • Sample Maximum Nutrient Density Meal Plan.

To get started today, all you have to do is join our new Optimising Nutrition Group here

Once you join, you will find the Nutritional Optimisation starter pack in the discovery section here.


Check out the following articles for more detail: