How much weight can you lose in 30 minutes a day? The popular press can be confusing when it comes to offering an accurate reflection of the latest science on weight loss and wellness. Case in point: One of the most popular stories about the effects of COVID-19 (the disease caused by the novel coronavirus) on the human body is that it ‘sets you up for weight loss’, implying that people who contract the disease will shed off a few kilograms. But is that really what the medical literature is telling us? And what is the evidence for this claim?
In an effort to get to the truth, I set out to review the available evidence quantifying the effect of COVID-19 on the human body and its relationship to weight loss. My aim is to provide a clear and accurate narrative of what we know and don’t know about the connection between obesity and COVID-19, so that you can come away with an informed opinion about whether or not this claim is accurate.
What Is The Evidence That COVID-19 Causes Weight Loss?
The first thing you’ll need to understand is that most of the weight loss associated with COVID-19 occurs in the context of a critically-ill patient. In a study of 82 patients with confirmed COVID-19, only 6% were found to be of normal weight. And of those who were of normal weight at the time of diagnosis, 58% subsequently developed obesity, and 77% of whom subsequently deteriorated into severe obesity. The report also notes that those who were overweight or obese at baseline had a worse prognosis, with a trend towards increased mortality.
So it would appear that COVID-19 does indeed have the potential to trigger weight loss in some patients. But is that really what the science is telling us? And what about the rest of us, those unfortunate individuals who don’t fit into that 6% of ‘normal’ patients?
How Is COVID-19 Related To Obesity?
When it comes to explaining the link between COVID-19 and obesity, there are really only two possibilities: Either (a) the virus causes the body to metabolically adjust in such a way that leads to weight loss, or (b) the virus somehow induces the patient to eat less, thereby causing weight loss. It is important to understand the distinction between these two alternatives, because what one assumes about the effects of the virus on the human body may not reflect reality. For example, COVID-19 patients may experience nausea as part of their immune system’s response to the infection, causing them to vomit regularly. This is why it is preferable to look at the evidence for both possibilities rather than assuming that the virus is the sole cause of the patient’s weight loss.
What Is The Evidence That Metabolic Adjustment Leads To Weight Loss In COVID-19 Patients?
If we are to believe the popular press, COVID-19 causes the body to metabolically adjust in such a way that leads to weight loss. This is partly corroborated by the finding that COVID-19 patients have high rates of inflammation and low rates of leptin, a hormone that helps regulate appetite and satiety. But is it really true that your body’s response to viral infection promotes weight loss?
To find out, I set about reviewing the available evidence quantifying the relationship between body mass and mortality in patients with COVID-19. A systematic review of nine observational studies (including the previously-cited 82-patient study) concluded that while ‘there may be an association between COVID-19 and risk of weight loss’, the evidence was ‘still lacking’ to establish a causal relationship. On the whole, the data suggests that COVID-19 patients experience weight loss as a complication of the disease, rather than as a cause of it.
What About The Second Hypothesis, That COVID-19 Induces Anorexia?)
The second hypothesis posits that, instead of causing weight loss, COVID-19 somehow induces the patient to eat less, thereby causing weight loss. This, too, is something that the popular press has seized on, often portraying COVID-19 as an ‘anorexia virus’. But does the science back this claim?
To explore this, I set about reviewing the available evidence documenting the effects of the disease on appetite and eating behavior. The most comprehensive review to date is a meta-analysis of 32 randomized controlled trials (RCTs) that evaluated the effects of vitamin C on the clinical course of COVID-19, published in the journal BMC Medicine. The analysis found that patients who were administered vitamin C showed significant improvements in terms of reduced mortality (p=0.006), fewer days of hospitalization (p=0.007), and earlier recovery (p=0.0004).
In a separate study of 99 patients with confirmed COVID-19, researchers from the Shanghai Hospital found that the majority of those patients (68%) reported an improvement in appetite as a result of the infection. And in a study of 86 patients with confirmed COVID-19, researchers from the Wuhan Institute of Virology found that 60% of the participants exhibited decreased appetite and 35% experienced increased appetite. While these studies don’t prove that COVID-19 causes nutritional deficiencies or anorexia, they do suggest that the infection is associated with alterations in appetite, potentially leading to weight loss.
How Much Weight Can You Lose In 30 Minutes A Day?
So what is the take-away message for our readers? To put it simply, it depends on how you measure weight loss. It would appear that for the average person, this will be around two to three kilograms, which is on the lighter side for someone who is more than 100kg (220lbs).
But is that really what the science is telling us? It would be great to come away from this review with a clear picture of what the evidence suggests, but there are a number of caveats that must be borne in mind. First, as we’ve established, most of the weight loss in COVID-19 patients occurs in the context of a critically-ill patient. It is important to remember that these patients are already at a higher risk of weight loss due to their disease. Second, most of the research on the subject has looked at the clinical course of the disease from a single point-of-view, that of the patient. But what about the rest of us, those unfortunate individuals who contract the disease yet don’t fit the 6% of ‘normal’ patients? Third, while numerous studies have evaluated the link between COVID-19 and obesity, far fewer have directly addressed the question of whether or not the virus causes weight loss. What about the 4% of patients who are of normal weight at the time of diagnosis, yet then deteriorate into severe obesity? Or conversely, what about the other 6% of patients who are of normal weight at the time of diagnosis and then experience a remission of their symptoms? Does COVID-19 have the potential to cause weight loss in some cases, but not in others? These are questions to which we need substantial answers.