How to Stop Your Metabolism Slowing Down When Dieting

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Tom Blackman Podcast episode 4 Stop your metabolism slowing down on a diet

There are 3 things that can slow down your metabolism quickly

  • Sedentary lifestyle
  • No resistance training
  • Low protein intake


These are contributing factors to a slow metabolism which you may be aware of.  What happens though when you are not aware of your metabolism slowing down?  You may be training in the gym 3-4 days per week, eating a higher protein diet and trying to keep active but your body is working against you.

What are the signs of a slow metabolism and what happens if you have it?

If your metabolism is slowing down rapidly you may feel amongst other symptoms


  • Slow and sluggish
  • Depressed
  • Tired
  • Low motivation to exercise
  • Constant fatigue which isn’t rectified by sleep
  • Frequent headaches


I have experienced all of these when dieting for bodybuilding shows but that was also because I was in a super high calorie deficit while I was trying to get into shredded condition for a competition.  Therefore it’s also worth nothing that you can feel these symptoms from a calorie deficit which is too high and adjusting your calories in may correct it easily.

How can you speed up or your metabolism to lose weight?

Many people mistakenly think that they have a slow metabolism when in fact they have just restricted their calories too much and the body is fighting back, a chronic slow metabolism is generally not the case.  I have worked with clients with PCOS (Poly Cystic Ovary Syndrome) and Hashimotos, both of which suppress metabolism in different ways.  


For these conditions thyroid medication is sometimes prescribed, for some instances of Hashimotos the normal prescribed medication Thyroxine (also referred to as T4) is not effective as the body does not have the ability to convert it into the more active Triiodothyronine (T3) so it’s worth checking this if you have this condition.  However I am not a doctor and I will not dispense medical advice, this is just something I’ve learned from having clients with the condition.


You can also speed up your metabolism by


  • Training with weights regularly
  • Increasing your Protein intake


These 2 things are how I normally approach slow metabolism issues in clients, but also it’s a general rule that I use with all clients anyway, there are numerous benefits from these 2 activities and I actively promote them as a weight loss tool.

The easiest way the body reduces metabolism is by reducing it’s NEAT activity

It’s important to point out that many cases of ‘slow metabolism’ are simply the body reducing your activity.  A slow metabolism would mean that your overall metabolic rate had reduced which is unlikely to a great degree.  Your Base Metabolic Rate is calculated using the following factors:


  • Height
  • Weight
  • Sex
  • Age


There’s only 2 of these that are likely to vary and it won’t be enough to drastically alter metabolic rate unless you lose over 7kg or somehow age 10 years overnight.  If you have kids though you might feel that you have aged a lot quite quickly.  


Your Base Metabolic Rate is multiplied by your Personal Activity Level (PAL) to give an estimate of your Energy Expenditure Rate (EER).  This is the figure that most calorie calculators will give you as your maintenance calories.  To lose weight you then eat less calories than you burn at maintenance which gives a calorie deficit.


Weight Loss = EER > Calories In (Fat Loss) = Calorie Deficit

Weight Gain = EER < Calories in (Muscle gain/Fat gain) = Calorie Surplus


To work out your calories for fat loss – Use my Calorie Calculator

To work out your calories for muscle gain – Use my Muscle Gain Calorie Calculator


The body tries to reduce the calorie deficit after a while by reducing your NEAT activity.  This is all the activity that is not keeping you alive (BMR).  It does this to bring you back to maintenance and so weight/fat is neither lost or gained, restoring balance.

How do we stop the metabolism slowing down or more specifically NEAT slowing down?

The easiest way to measure your NEAT activity is via a step counter device.  This is a wearable device that you wear on your wrist or belt that monitors your movement.  By tracking and logging your daily steps and comparing the average each week you will start to see your average movement for the weeks.  If you start to see a trend where the average movement is going down then you know that the body is trying to slow down NEAT activity.


Therefore a very simple fix to keep yourself in check when dieting is to monitor steps.


I go into more detail in the video and podcast below.

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