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Calorie Adjustments in a Fat Loss Phase

Performance Training Personal Training

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Next in our insight series we begin to get practical in terms of how we approach fat loss phases and calorie adjustments once they are up and running. Specifically in this weeks insight we will look at what types of adjustments we can and should make depending on the rate of loss and intended outcome.

If this is your first read of an insight within this series, we’d strongly recommend looking back through the previous posts to provide some clear context for this insight (1,2,3,4,5,6)

In Upper and Lower Limits of Fat Loss, we outlined the potential risks associated with losing body weight during a fat loss phase at too quick, and too slow a rate. 

When losing at rates slower than 0.5% of our bodyweight per week, we encounter issues regarding the actual measurement and tracking of the loss with most scales only being calibrated to 1 pound increments. Measuring if any change is actually occurring at these slower rates unlikely to give reliable feedback as to what is actually occurring. We also highlighted how the speed of fat loss increases with faster rates, eg. the more weight we lose the more fat loss we also lose. Individuals are unlikely to encounter risks to excessive muscle mass loss at rates below 1% of bodyweight per week. 

At rates above 1%, not only do we increase the likelihood of muscle mass loss, but the knock-on effect in terms of significant lowering of calories and food volumes create a scenario in which radical hunger and both physical and psychological stress is heightened. As diet fatigue continues at faster rates, we see a lowering in metabolism rates and non-exercise activity as the brain tries to regulate energy output. Training performance, hormonal status and our general health all decrease the further into a diet we go at rates faster than 1%. These factors culminate in an increased likelihood of diet rebound once a phase ends.

We ended this previous insight with five key recommendations:

  1. Losing at rates below 0.5% is possible, yet impractical when it is more efficient and effective to lose at faster rates
  2. Losing at rates above 1% is possible, however there are potentially severe implications to muscle mass retention, hormonal status and overall health.
  3. Fat loss phases of less than 2 weeks is likely to result in only temporary shifts in body water, NOT actual long term fat loss.
  4. Fat loss phases longer than 4-6 months is both physically and psychologically demanding, with an decrease in muscle retention and training performance likely to occur.
  5. 2-4 months of continual loss with 4-12% weight loss is likely to be ideal in most circumstances. Longer phases require slower rates (0.5-0.75%), shorter phases may benefit from utilising higher rates (0.75-1%). Losing 8-10% of bodyweight in a single phase is likely the upper limit.

With these plans in place and clearly outlined we can begin the process of a fat loss phase. For todays insight we will use the following client example to help us work through this practically.

Client A:

5ft 7 


Current Weight: 90kg (200lbs)

Target Weight: 68kg (150lbs)

Total Target Amount: 22kg (50lbs)

Time Frame: 12 Months


Example Fat Loss Phase Structure

Phase One – 10 Week Fat Loss Phase: 8% Target Loss (83 kg/182lbs)

Phase Two – 8 Week Maintenance: Stay within 1% bodyweight (82-84kg/180-184lbs)

Phase Three – 10 Week Fat Loss Phase: 8% Target Loss (75kg/165lbs)

Phase Four – 8 Week Maintenance: Stay within 1% bodyweight (74-76kg/162-167lbs)

Phase Five – 10 Week Fat Loss Phase: 8% Target Loss (68kg/150lbs)

Maintenance of New Body Weight


From the information above, we know we have clear planned rates of weight loss. We also know where we want to end up within any one phase, and as a result have an rate of weight loss per week that we can target into. 

Our Phase One target is a weekly weight loss rate of ~0.8% (~8% over 10 weeks) with an initial target of between 6-8kg (13-17lbs) loss in total across the duration of this initial phase.

Anyone who has been through an attempt at fat loss previous will attest to the fact that results are often non-linear. One week it may be 2-3lbs loss, one week may see no change, others may see a slight increase. This is owning to the variation that is in play between our calorie intake, daily activity levels, exercise intensity and duration, sleep and stress levels. Each of which plays a part in the rates at which we can expect to loss weight within any single week.

However, to prevent a weight loss phase simply fading out without adjusting to accommodate for this variation, we need to set acceptable boundaries for change. 

Therefore, if we take our estimated 0.8% rate of bodyweight loss per week, we can attach an upper and lower limit from which we can make adjustments from. A band of 0.2% above and below our estimated rate (0.8%), keeps us on track for when things are moving too far outside of our control. 

With this upper and lower boundary in place, we can begin to establish guidelines regarding how we adjust depending on the rate of weight loss versus our target weight.

At the simplest level, if the rate of weight loss is within our accepted band of ranges, we could choose to continue the process and without adjustments knowing we are trending in the right direction. If our rate of weight loss falls below the acceptable band (eg. losing weight too quick), we can adjust calories up to slow the rate of weight loss to more manageable levels. Likewise if our rate of loss falls above the band (eg. not losing enough) we can adjust calories down. We can simply then repeat this process week on week to keep us within range.

By putting this simple formula into place, we limit wasted time and keep moving continuously in the same direction almost guaranteeing the hypocaloric conditions needed for fat loss to occur.

We do have the capacity however to take step further and look at overlaying each weeks weight loss and see the specifics of what we need to do when adjusting calories up and down.

Adjusting Calories Down

In our example below, we can see that the recorded bodyweight has creeped above not only the target rate of weight loss, but also now is above the lower boundary (0.6%) of slower rate of weight loss. If our individual continues to lose at this rate, they will not intercept the target goal within the time period outlined within this phase. It may take 2-3x longer to achieve the same outcome. We’re therefore needing to address the issue of how to adjust calories down.

The amount in which we restrict calories is likely to be impacted by the percentage above the target rate that we are. If we are only just above the lower boundary target rate (0.6%), a small calorie deficit should be sufficient to bring the trend back on track. In this case, reducing calories by 10% (eg. 2000kcal target reduced by 200kcals) should be enough. 

If we are below the lower boundary target rate (0.6%) but still quite above the target rate (0.8%), it may still be beneficial in reducing calories by 10% to ensure the trend line is moving in the right direction and we still will reach the approximately the target goal.

If we are significantly above the target rate and the lower boundary with the trend line for weight loss very likely to fall outside of the target range of weight loss (in this example 180-187lbs), a reduction of 20% (2000 kcal dropped by 400 kcal to 1600 kcal) may be beneficial to ensure the goal is reached within the timeframe needed.

Adjusting Calories Down

When it comes to adjusting of calories up, in which we are losing at a rate that exceeds either the upper boundary (1%), or target rate of loss (0.8%), we can apply a similar approach based on the rate of weight loss being recorded.

If we are just under the rate of target weight loss, we needn’t change anything in terms of calories, we are safely losing at a rate that is acceptable and likely will intercept the rate of weight loss in the future weeks as some of the associated factors of weight loss phases take place (slowing metabolism, lowering of NEAT etc.)

If we are losing at a rate quicker than our expected target rate of weight loss such as in the example below, but we still are following a slope that will intercept a rate of weight loss that is accepted (eg. 0.9%), again we don’t need to be over-reactionary knowing that this is a safe rate of loss that is manageable in the timeframe outlined and will likely begin to level out as the weeks continue.

Our one example that needs intervention however, is if the rate of loss falls outside of the intercept of our our goal weight or falls significantly below it. At this point, we are running the risk of encountering the negative effects associated with rapid rates of weight loss (greater than 1% per week). In this example we should look to increase calories by 10% per day to bring the rate of weight loss back to more acceptable levels within the time frame of the phase.

In a single phase, we may need to make more than one adjustment to accommodate for changes occurring within the process, however structure and guidelines exist underneath to make sure we aren’t excessively reactionary to any one single recorded bodyweight.

In each of these examples, the end goal needs to be kept in mind with the focus remaining on are we still on track to hit the target weight within an acceptable window without disregarding any of our recommendations? 

Now we have established how we adjust calories up and down within a fat loss phase, our next insight will build further and look at the the individuals adjustments we can make to macronutrients, the composition of the food we eat and the nutrient timing we use to maximise outcomes and maintain adherence during.

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