Do antihistamines make you gain weight?

Man Sneezing“Achoo!!”

Some folks have allergies that flare up on a seasonal basis. This spring has certainly not been kind to this group.

But if you’re like me, battling your allergies is a year-round affair. The common antihistaimnes available at every drug store, including Cleratin, Reactine, and Aerius, have all at one point or another helped me breathe. More recently, I’ve also been using saline nasal rinses as well as intranasal corticosteroid sprays.

However, the off-the-shelf antihistamines many of us take to get us through allergy season have an additional effect: they may increase appetite. Despite the fact that increased appetite is a fairly well-known side-effect of antihistamines, the packaging of my allergy meds had no mention of this.

Histamine is a neurotransmitter which, in addition to mediating the inflammatory response, and thus symptoms of allergies, suppresses appetite. Thus, antihistamines, which work by blocking the H1 histamine receptor, may remove this appetite suppressing signal.

Not surprisingly, a paper published in the journal Obesity suggests a possible link between the use of anti-histamines and body weight.

In the paper, Ratliff and colleagues used data from the National Health and Nutrition Examination Survey during the 2005-2006 years.

“268 adults (174 females and 94 males) reported use of an H1 antihistamine and completed all outcome measure components. 599 age- and gender-matched controls (401 females and 198 males) were used as a comparison for body measurements, plasma glucose, insulin concentrations, and lipid levels.”

What did they find?

“After adjusting for gender, prescription H1 antihistamine users had significantly higher weight (P < 0.001), BMI (P < 0.001), waist circumference (P < 0.001), and insulin levels (P < 0.005) compared to healthy controls.”

Specifically, controlling for age and gender, those who take anti-histamines were 55% more likely to be overweight than their non-allergy-suffering peers.

However, the increased risk of overweight with antihistamine use was more pronounced for men than women (70% vs 21% increased likelihood).

No differences between the groups were observed for any of the other metabolic risk factors studied.

Of course, as I mention often with this type of study, the results merely suggest a correlation between antihistamine use and body weight; countless other confounding factors may be playing a role. Nevertheless, the preliminary observation is intriguing.

In addition to the direct effect on appetite stimulation, the increased weight observed with antihistamines may also be due to increased sedation, suggest the authors. Theoretically, at least, the increased sedation may lead to a decreased energy expenditure and weight gain. However, most current antihistamines are only mildly sedative at best.

I have tried to think back to times when I take antihistamines and recount whether I had an increased appetite or sedation, and I’m not sure my personal experiences corroborate this observation. Then again, since I’m a fairly chronic antihistamine user, I’m probably unlikely to notice this change.

For the sake of proper breathing, I’ll stick to my anti-histamines.

I wonder if any of our readers have noted a change in appetite or wakefulness when taking antihistamines.



Ratliff, J., Barber, J., Palmese, L., Reutenauer, E., & Tek, C. (2010). Association of Prescription H1 Antihistamine Use With Obesity: Results From the National Health and Nutrition Examination Survey Obesity, 18 (12), 2398-2400 DOI:10.1038/oby.2010.176

Category: News | 4 Comments

Too much sitting may increase cancer risk

Lazy boyYou’ve heard it here more than once: sitting too much is bad for you. Unfortunately, much of our everyday life is comprised of prolonged sitting – from your car, to your desk, to your dining table, to your couch. There’s just no escaping the temptation to sit. Sometimes, despite your best efforts, sitting is the only socially acceptable option. (Ever tried standing in a movie theatre or at dinner in a restaurant? This guy has)

Sitting too much increases your risk of a variety of diseases and early mortality even if you are at a healthy weight and you regularly exercise. For instance, as Travis previously summarized, a “longitudinal study from Australia reports that each hour of daily television viewing is associated with an 11% increase in the risk of all-cause mortality regardless of age, sex, waist circumference, and physical activity level.”

Some have gone as far to suggest that sitting is the new smoking. How is that for an ominous metaphor?

In case you needed more proof that excess sitting is, in fact, killing you – here it is, courtesy of a new study published in the Journal of the National Cancer Institute: too much sitting is also associated with an increased risk of certain cancers.

In the study, the authors analyzed data from 43 individual studies including a total of 68 936 cancer cases (a study or studies, or a meta-analysis in science-geek parlance). Across all these studies they compared the risk of a specific cancer in the most versus the least sedentary group.

Comparing the highest levels of sedentary behavior to the lowest, the study observed a significantly higher risk for three types of cancers of the colon, endometrium, and lung.

Specifically, for each 2-hr increase in daily sitting time, the risk for colon cancer, endometrial cancer, and lung cancer, increased by 8%, 10%, and 6%, respectively.

Similar observations were reported for the specific behaviours of TV viewing time and occupational sitting time as well as total sitting time.

As has been described in other similar studies, these associations were true regardless of how much individuals exercised. In other words, not only do we all need to try to be physically active, we have to ensure we’re not falling into the category of an active couch-potato. That is, one who exercises for an hour a day, but spends the rest of his/her time with their butt firmly planted in a chair or couch.

As always, we have to keep in mind the limitations of this type of study. One of the first lessons we all learn in an entry statistics class is that correlation does not equal causation. An increased risk of certain cancers with increased idle time has been observed consistently across many studies, but this does not definitively prove that sitting causes cancer.

Nevertheless, limited lab studies in humans and animals have provided some insights into the mechanisms by which this might happen. The authors of this paper suggest a number of ways in which sitting may lead to cancer – with the mechanism potentially differing based on the type of cancer in discussion. At this point, however, the picture remains blurry.

What is less unclear is the fact that we’d all likely do ourselves a favour by spending less time on our ischial tuberosities (sitting bones).


Daniela Schmid, Michael F. Leitzmann. Television Viewing and Time Spent Sedentary in Relation to Cancer Risk: A Meta-analysis. Journal of National Cancer Institute. 2014. DOI:10.1093/jnci/dju098

Category: News, Obesity Research, Peer Reviewed Research, Physical Activity, Sedentary Behaviour | 1 Comment

New Study: High Levels of Air Pollution Associated with Lower Levels of Physical Activity

Today’s post comes from Dr Jennifer D Roberts.  You can find more on Jennifer at the bottom of this post.

Physical inactivity, ambient air pollution and obesity are modifiable risk factors for non-communicable diseases, with the first accounting for more than three million annual deaths.  Recently, we identified an association between increased ambient air pollution, specifically particulate matter 2.5 (PM2.5), and reduced leisure-time physical activity within the U.SNumerous scientific studies have linked PM2.5 exposure to a variety of health problems including irregular heartbeat, aggravated asthma, and premature death.  However, many of these studies have illustrated these effects in a resting, inactive state, or among elite athletes and the data examining the effects of poor air quality among larger individuals or in real-world physically active settings are meager.

Figure 1. Pollution in the USA (Roberts et al., PLOS ONE)

Figure 1. PM 2.5 Air pollution in the USA.  Darker blue represents higher levels of pollution. (Roberts et al., PLOS ONE)

Figure 2

Figure 2. Prevalence of leisure-time physical inactivity. Darker orange represents higher level of physical inactivity.


This research found that the highest concentrations of PM2.5 were in the upper Atlantic, Midwest, and the South, along with a small cluster in Southern California (Figure 1).  By comparison, Figure 2 shows the unweighted prevalence of leisure-time physical inactivity in U.S. counties.  Both maps illustrate higher levels of PM2.5 and leisure-time physical inactivity in the South and Midwest.  

Our study findings were compelling because they indicated that the magnitude of this inverse association between air pollution and physical activity was more pronounced among the normal or healthy weight, as opposed to overweight or obese individuals.  Specifically, for these leaner individuals, we estimated a 16–35% relative increase in the odds of leisure-time physical inactivity per exposure class increase of PM2.5 after controlling for several variables, such as age, sex, race, income, seasonality, and urbanization (Figure 3).  We recently published our findings in PLOS ONE this past March (DOI: 10.1371/journal.pone.0090143).

Odds of Physical Inactivity By Pollution Exposure and Body Weight.  Data are adjusted for adjusted for age, sex, race/ethnicity, education, annual income, marital status, seasonality, geographic region, general health status, smoking, disability, asthma, urbanization, and the other air pollutants. (Robertson et al., PLOS ONE)

Figure 3. Odds of Physical Inactivity By  PM 2.5 Air Pollution Exposure and Body Weight. Data are adjusted for age, sex, race/ethnicity, education, annual income, marital status, seasonality, geographic region, general health status, smoking, disability, asthma, urbanization, and the other air pollutants. (Robertson et al., PLOS ONE)

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Category: Guest Post, Obesity Research, Peer Reviewed Research, Physical Activity | Tagged | 2 Comments

Sorry everyone – LeBron’s muscle cramps were NOT caused by dehydration or salt loss

LeBron James (Image by Steve Jurvetson)

LeBron James (Image by Steve Jurvetson)

Last week during game one of the NBA Finals between the Miami Heat and San Antonio Spurs, the air conditioning system in the AT&T Center wasn’t working properly. As a result, the normally cool arena was a sweltering 90 degrees fahrenheit (~30 degrees Celsius). Miami’s LeBron James suffered a debilitating bout of muscle cramps, and had to leave the game. LeBron James is the single most dominant basketball player of his generation. So when he misses a significant portion of one of the most important games of the year, it is a Big Deal. Miami went on to lose the game 110 to 95.

Almost immediately, commentators went into a frenzy discussing how the heat and related dehydration/salt loss caused King James’ cramps (in the above video, the heat is mentioned several times within seconds of James cramping up). This article from ESPN, was pretty typical of the coverage that I saw online:

Miami Heat forward LeBron James was forced to exit early from Game 1 of the NBA Finals because of severe leg cramping caused by extremely warm temperatures after the air conditioning in the arena malfunctioned.

Or take this article, titled “Why heat cramps crushed LeBron”:

“In a regular game, professional athletes lose an extraordinary amount of fluid and electrolytes,” says Dr Michael Bergeron, executive director of the Sanford Sports Science Institute. “Playing in hot and humid conditions can push a player’s fluid and electrolyte loss to a dangerous level.” As dehydration sets in, subtle twitches or cramping can progressively turn into painful muscle spasms.

The prevailing wisdom being that the heat caused dehydration and/or electrolyte loss, which caused his muscle cramps. The analysis has been fast and furious (the classiest was Gatorade pointing out on Twitter that people who consume their sugar water sports drink can “take the heat” – LeBron is sponsored by Powerade), but most of it seems to miss a crucially important point: research suggests that exercise-related muscle cramps are not caused by dehydration or electrolyte loss (I was surprised that even articles explaining “the science of muscle cramps” largely sidestepped the issue).

The real explanation is way less sexy: exercise induced muscle cramps are caused by plain old fatigue.

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Category: News, Peer Reviewed Research, Physical Activity | Tagged | 8 Comments

Is it safe to exercise when pregnant?

Not my wife (Image by seandreilinger)

Not my wife (Image by seandreilinger)

The short answer  is yes – it is absolutely safe to exercise while pregnant.  It is also very beneficial.  There are a few situations that you want to avoid (e.g. maximal exercise, overheating, etc), although I can’t imagine many pregnant women choosing to engage in those types of exercise anyway.

These and other topics are discussed today in the latest installment of the Obesity Panacea podcast.  This time I am joined by my friend and colleague Dr Zach Ferraro.  Zach’s research interests include physical activity and weight management during pregnancy.  The impetus for this podcast was the fact that my wife is pregnant (!!!) with our first baby, and we were both curious about how physically active she could/should be while pregnant.  In the podcast Zach and I talk about some of the questions that Daun and I had, the types of activities that are recommended for pregnant women, and also how to recognize if you’re doing too much.

Daun and I have always been very physically active (we met on a varsity cross country team), she even moreso than me.  She’s cycled across Canada, can portage a canoe solo (I find this far more impressive than she does), etc. So it was really important for us to know what types of exercise are safe/potentially unsafe for a pregnant woman.  On that note, I’d like to remind people that  Zach is not a physician, so he was only able to give general info, rather than specific info for Daun (which I imagine will also make the podcast more useful for others).

Let me be the first to point out the irony of 2 men discussing pregnancy – my wife had hoped to join us for the podcast, but wasn’t feeling well the night that we did the podcast (we did the podcast at the end of the first trimester, during what was probably the worst week of the whole pregnancy… we’re now into the 3rd trimester and she is feeling much better). But many of the topics we discuss were ones that she had asked us to include in the podcast.

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Category: Interview, nutrition, Obesity Research, Physical Activity, Podcast | Tagged | 2 Comments

Cycling is safer than you think (but not as safe as it should be)

Image by Wolfgang Staudt

Last week there was a tragic and fatal bike accident here in Halifax.  As avid road cyclists, these sorts of accidents always hit home for my wife and I.  Even moreso in this case, as the cyclist’s description (an elementary-school teacher and cycling enthusiast in her early 30′s) is also an apt description for my wife.

Although the cause of the crash is still unclear (the cyclist was hit by a truck turning right, although no word yet on whether anyone was at fault), these sorts of accidents drive home the fact that riding a bike can, at times, be a dangerous activity.  And so, I thought this would be a good time to revisit just how dangerous cycling is, when compared to other modes of transportation.

The most useful information that I’ve encountered on this topic is from a paper in Environmental Health Perspectives which examines whether the benefits of increased cycling (increased physical activity) outweigh the risks (both in terms of accidents and exposure to pollutants for individual cyclists).  To calculate these numbers, the authors examine changes in mortality at both the population level, and for individual cyclists, if 12.5% of current short car trips in the Netherlands were to be performed by cycling instead.

So, what did they find?

The authors report that for most adults, the risk of death when cycling is about 4.3x higher than if the same trip were being made by car (YIKES!). However, we’ve got to remember that commuters not only pose a risk to themselves – they also post a risk to other road users.  And if you’re going to be hit by a vehicle, a Cervelo is going to do you a lot less harm than a Corolla!  There is a reason why you don’t hear about out-of-control cyclists taking out a swath of pedestrians.  So with an increase in the number of trips made by bike, the increased mortality among cyclists due to traffic accidents is offset by the reduced mortality among the general population who would be less likely to be run over crossing the street (interestingly, if it were high risk young drivers who were to switch from driving to cycling, it would actually save lives!).

Now while the risk of being in an accident is higher for cyclists, it must be remembered that they are also likely to be getting increased levels of health promoting physical activity, and substantially reducing their volume of sedentary time.  In fact, the risk of death due to physical inactivity among active commuters is estimated to be 10-50% lower than in non-active commuters – a pretty substantial health benefit!

So will cycling to work make your life longer or shorter?  On average, the risk due to car accidents will reduce your life expectancy by just 5-9 days.   Being exposed to air pollution during your commute could cost you another 8-40 days.  But the physical activity in your commute would actually increase your life expectancy by up to 14 months! Overall, the health benefits of active commuting by bike are 9 times greater than the risks!

Lest that you think that this is only true in the cycling utopia that is the Netherlands, similar studies have also suggested that the benefits of cycling outweigh the dangers in countries ranging from Spain to India and the UK.  Just this week it was reported that after 8.75 million trips covering more than 14 million miles, there has yet to be a single fatality associated with the new Citi bike-share program in New York City (there have been only 100 reported accidents so far, and only 25 of those warranted a trip to the emergency room).  When you consider that the people most likely to use a bike-share program are tourists and other individuals who don’t spend a lot of time on a bike, those results are very heartening.  Especially when you take into account the many failings of urban cycling in North America (see videos below).

What’s the take-home message?

Cycling is obviously more dangerous that it should be, something which needs desperately to be addressed.  But if you decide to commute by bicycle on a regular basis, you are far more likely to improve your health and prolong your life via increased physical activity than you are to shorten your life by getting involved in an accident.  It is interesting and extremely important to note that the number of cyclists on the road is inversely related to the number of car/bike collisions  – so the more of us that get out on the roads, the less likely we are to get in an accident.

And if you do choose to cycle more regularly (which I definitely think you should!), please wear a helmet and obey traffic laws – especially stop signs.  Those two factors alone will go a long way to preventing some cycling related deaths.

Today’s post is an update from a post published on Obesity Panacea in September of 2010.


Category: News | 6 Comments