Is cortisol to blame for stubborn weight gain?
In the health industry, particularly among ‘health guru’ circles, it’s believed that elevated cortisol is responsible for stubborn weight gain, particularly belly fat, that is near impossible to shift. But is this accurate? And will active reduction in cortisol result in ease of fat loss?
While cortisol definitely plays a role as ‘traffic director‘ for where fat is placed, it doesn’t appear to be the sole reason for impossible weight loss. It’s common to hear stories about those who reduced their stress, or took X supplement to reduce cortisol & the fat ‘just melted away‘ . If this is true, then surely anyone without stress would never experience issues with resistant fat loss, but this is not what we see. It is not unusual to run lab work on an individual & find that cortisol is great, yet they still cannot achieve desired fat loss.
So why is there so much confusion about cortisol & fat loss, and more importantly, what does the science say?
Cortisol has many functions in the body. It initiates the waking response in the morning, modulates the immune system & keeps the body fulled with energy during chronic stress.
Under the stress response, your adrenals release adrenaline which signals glucagon & the release of glycogen from liver (primarily) & muscle cells; this response floods your bloodstream with glucose to fuel the fight/flight response. In ‘normal’ amounts, cortisol & ‘stress hormones’ actually have many beneficial actions:
maintains metabolism
balances blood sugar
maintains blood pressure
reduces inflammation
keeps us alert & reduces fatigue
Excess cortisol can cause seemingly rapid weight gain, but it is not what you may think.
A diagnosable excess of cortisol is Cushing’s Disease, often seen as a condition of central adiposity & fat gain only, however Cushing’s also includes considerable fluid retention. This can also be an aspect of rapid, high-stress-related weight gain for a lot of individuals as the adrenals signal the kidneys to reserve sodium & water. The key here is that the weight gain is partially fluid retention, not solely fat tissue; a key factor that can have most of us panicking & jumping to the conclusion that we have indeed gained weight, seemingly overnight. This is the type of weight that also seemingly disappears overnight, before returning once again to mess with our heads.
How about under eating? Can’t eating too little make your cortisol rise & cause your body to ‘hold onto fat‘?
A 2016 systematic review & meta analysis revealed that Intermittent Fasting (IF), Low Calorie Diets (LCD) & Very Low Calorie Diets (VLCD) indeed caused a transient increase in cortisol. This means that cortisol is elevated for an initial period, then returns to baseline, and in the study above, returned to baseline after several weeks on the diet. Cortisol elevation is more severe in IF than the medial response with a typical LCD. Despite the approached used, achieving a calorie deficit has shown to be the defining factor for fat loss.
On the topic of cortisol and weight loss, how can we not give a mention to the world’s favourite hot beverage, coffee. It appears that caffeine consumption, commonly believed to elevate cortisol & lead to fat gain, is not that clear cut; research has shown it actually leads to increased energy expenditure & weight loss. If this is so, then how can elevated cortisol alone, lead to weight gain or weight loss resistance?
Elevated cortisol is commonly recorded in those with obesity (including above mentioned Cushing’s Disease), leading to widespread belief that the elevated cortisol is the cause & that if cortisol remains high, weight loss is hindered because of the cortisol. A common thought is the link between high cortisol, high blood sugar & high insulin…leads to the decreased beta oxidation of fatty acids…and the common thought that elevated insulin, therefore, keeps you from losing body fat…hello Keto & Low Carb communities. Insulin is another misrepresented issue in fat loss, but we’ll save that for another post.
The most likely culprit is the effect of acute & chronic stress on emotional & physiological hunger cues. A 2020 research paper examined the psychological aspects of chronic stress & feeding behaviour. Subjects were divided into high or low cortisol reactors & further into obese & non obese groups. High cortisol reactors in the obese group consumed significantly more than their low cortisol counterparts. However, they also consumed significantly more high calorie foods than high cortisol responders in the non-obese group. As expected, the results were not linear & were full of nuance; meaning that stress affects people differently. The main point to consider is that cortisol does not appear to be the cause of weight gain, it merely amplifies feeding behaviours in those susceptible to high energy foods & high overall food intake when under stress.
When exposed to stress, some are more susceptible to comfort seeking behaviour while others experience lowered hunger signalling; this is not entirely surprising as our world becomes faster. Today, doing progressively more is praised & downtime is seen as laziness. At some stage, our executive brain exhausts, the limbic system takes over (based on emotions & subconscious patterns), in steps Dopamine…and , well you know the rest of the story…in a few minutes you can have an Uber driver on the way with a load of the worlds’ finest & most sublimely marketed emotional crutches…Maccas, Ben & Jerrys, Cadbury’s. In just as much time, you can consume a huge amount of calories which come with low protein & fibre, so you’ll receive a mighty dopamine boost, but low satiety & likely feel hungry again in the near future.
So the moral of the story?
Cortisol is not always the bad guy.
For weight management alone, solely focussing on reducing cortisol whilst not considering overall energy balance & lifestyle factors may just be doing you a huge disservice; this will keep you in the cycle of chasing the next ‘miracle‘ supplement. Yes, you may be stressed, but overlooking the basics for the next quick fix won’t get you any closer to your goal.
To get you started, take a quick stock of your wind-down habits after a stressful day at work. For many of us, there are comforting snacks waiting for us when we get home; to soothe us as we go about the task of preparing dinner & finishing any lingering tasks for the day. Most commonly, this soothing comfort is cheese & crackers along with a glass of wine. Although delicious & perfectly fine in moderation, this blissful trio can pack quite an energy punch and most of us will have little recollection of exactly how much we consumed. This type of pattern is where to pay attention, cortisol is (largely) just the driver leading to habitual comfort-seeking behaviours.