Episode 55 – Can Hormones Be the Reason You Aren’t Losing Weight?

Key Topics Covered


  • Is the cause of weight loss/gain “calories in vs calories out” or hormones?
  • Hormones are factored in already to calories in vs calories out.

What hormones could play a role? 

  • Thyroid hormones
  • Insulin
  • Cortisol
  • Estrogen
  • Testosterone
  • Leptin
  • Ghrelin and other hunger/fullness hormones 

Thyroid hormones 

  • Your thyroid hormones influence a lot of functions in the body. 
  • Functions that require energy/calories  
  • Therefore thyroid hormones will impact metabolism 
  • Obviously super complex – so we are going to do the clif notes version  

Hypothyroidism is the state of low thyroid hormones  

  • = Reduces metabolism since the metabolic processes are being interrupted  
  • Often associated with weight gain. 
  • + can make it harder to lose weight due to lower caloric needs  
  • For context, the research I have seen has shown as much as a 20% reduction in TDEE due to underactive thyroid 
  • The reduction in calorie expenditure actually aligns with the symptoms of hypothyroidism e.g. fatigue, brain fog, constipation and feeling cold more easily. 


  • A lot of statements like “The key to weight loss success is to control your insulin, specifically, keeping insulin as low as possible.” Often followed by “the solution is to keep carbs as low as possible” 
  • Insulin’s main role is to take glucose from the blood and put it into muscle and/or fat cells to be stored for later use 
  • Insulin inhibits lypolysis, which is the breakdown of fat. 
  • It also increases lipogensis, which involves taking fat from the blood to be stored as body fat. 
  • You can see why this sounds scary. 
  • But the reason insulin inhibits fat breakdown is because you just consumed nutrients in the form of protein or carbs or whatever. It is more efficient to use those instead of your body’s stores.  
  • And it is not like only one thing can happen at a time. Other hormones like glucagon do the opposite of insulin and stimulate lipolysis. These hormones do not just completely switch off because insulin is present. Think of this process more like a dimmer switch on light instead of an on/off switch.  
  • It’s a complex interplay with a LOT of factors going on. And it is also worth mentioning that insulin can only store something that is available to be stored. If you are in a calorie deficit each day for example, there is less total glucose and fat available to be stored each day. 
  • It is also worth noting that in cases where insulin is typically higher than normal such as those with diabetes and insulin resistance, higher vs lower carb diets still result in the same fat loss when total calories and protein are matched.  
  • As an example of this, a metabolic ward study by Kevin Hall and colleagues was done under those conditions (same total calories – keto vs low fat). Both groups lost the same amount of fat, even though insulin was 22% lower in the low carb group than the low fat group. 
  • Some people also argue that insulin makes people hungrier, which leads to higher calorie intake, but the evidence does not support that. 


  • Typically thought of as a stress hormone.  
  • Has both positives (reducing inflammation) and negatives, even though it is often thought of as a negative. 

Cushing’s syndrome (high cortisol levels) 

  • Weight gain can occur, particularly because it increases appetite and cravings.  
  • Also comes alongside other aspects such as fatigue, hypertension, irritability, thinning hair and it is also known for causing a rounding of the face. 

Addison’s disease (low cortisol levels) 

  • Low appetite and weight loss can occur 

Stress induced elevated cortisol does  

  • Seem to increase calorie intake on average too 
  • But stress is linked with both weight gain AND weight loss 
  • In research on obesity 
  • Obese subjects typically report higher stress than controls  
    • but no correlation with cortisol levels are found on average.  
  • So the assumption that stress = cortisol is a little out of sync.  
  • This research also does not find a link between cortisol and obesity on average. That doesn’t mean it CAN’T be a cause, just that it isn’t a common factor. 

It also plays a role in water regulation as well e.g. increased cortisol = increased water retention. 

Hunger hormones: Leptin and Ghrelin 

  • Leptin = fullness hormone 
  • Ghrelin = hunger hormone 
  • Ghrelin typically increases when people consume too few calories or too little food volume and decreases when they consume too much. It is a way of regulating our appetite. 
  • Leptin is considered a fullness hormone. And based on this logic, it makes sense to assume that those who are larger might be less likely to have high leptin. But technically people with more body fat actually have MORE leptin. Leptin resistance seems to be higher though. 
  • Leptin also plays a role in energy expenditure – more leptin = more energy expenditure. 
  • People also tried to use leptin as a weight loss injection, but it seemed like after about a two week period, injecting leptin was no longer effective. 
  • Because of this, it is hard to pinpoint low leptin as being a relevant factor.  
  • Ghrelin is also hit and missLevels of ghrelin are not typically higher in those with higher body weight. There is speculation that ghrelin sensitivity might be higher, but there also is not a lot of evidence for that.  
  • There are other hormones (e.g. Neuropeptide Y (NPY), Glucagon-Like Peptide (GLP-1), Cholecystokinin (CCK), Peptide YY) that also play a role in this too making it a complex area. For example, as hunger increases over the course of a diet, ghrelin does not always increase alongside it.  
  • There are exceptions to this e.g. those with Prader Willi syndrome have high grehlin levels. Those who have had bariatric surgery often have lower Ghrelin levels. 

Estrogen and testosterone 


  • Plays a role in body fat distribution, especially women going into menopause are going to have a different body fat distribution.
  • Technically anabolic – higher estrogen levels can increase strength.

Does the pill lead to weight gain?

  • Temporary side effect of increased fluid retention is common. – especially oestrogen based ones 
  • Progesterone based contraception can stimulate appetite  
  • But a review of 45 studies on the topic found no link between the pill and long term weight gain, when compared to placebo.  
  • But obviously it is listed as a potential side effect on a lot of contraception – so we can’t say there is no merit to these claims 
  • How hormonal contraception can effect metabolic rate, hunger, mood etc is a minefield  


  • Test is normally linked with gaining size.  
  • Research on testosterone supplementation in those who are obese and have low testosterone has indicated that it actually helps weight loss. In a review on that topic, it identified that a large percentage of men who are obese have low testosterone. On average, those who are classified as obese have 30% lower testosterone. 


So can hormones be the reason you aren’t losing weight? 

  • We do think it’s a factor and should be considered when trying to lose weight. There are a multitude of effects that hormones can have, however we do consider these when calculating calories in vs calories out.

Relevant Links/Resources

Studies Mentioned:

Related Blog Posts: