Low Fat diets are causing obesity! Really?

It’s hard to know who to believe when it comes to nutrition information these days.  Everyone is an expert, and some “experts” are dishing out advice against low fat diets.  These folks claim that since the introduction of low fat diets, the obesity rate has as much as tripled in North America.  They blame low fat diets for the climb in obesity rates. I’m here to tell you that these experts are dishing out fiction.  Why am I sure of this?  Because the “facts” they’re telling you are not accurate.  Firstly, for their argument to make sense, low fat diets would have to be on the rise, and at least in Canada, they are not.  Secondly, whereas weight gain and weight loss is a complex issue, all of these complexities come down to the physiological fact: calories in, calories out.  Now, some of these “experts” will tell you that “a calorie is a calorie is a lie.”  While yes, calorie counting is a difficult idea to grasp, it remains one of the most accurate ways to maintain weight or help with weight loss.  Calories in food are not the be all and end all of weight loss, but they remain important pieces of information.  I’m not saying you have to count all the calories you eat; however, keeping an eye on the number – or hiring a dietitian to do so – can be a good step in your weight loss journey.

OK, so why is the idea that low fat diets cause obesity simply untrue?  The easiest answer is that consumption of fat has actually increased – right along with obesity rates – in the last decade.  According to a report entitled “Canadian Consumer Trends in Obesity and Food Consumption,” (put out by the Government of Alberta), fat consumption increased a whopping 22% from 1991 to 2002.  In the same time period, obesity rates tripled in Canada.  How about the US?  Well, here is where the argument for low fat diets causing obesity seems to to gain some ground.  According to a report by the Centres of Disease Control (CDC), entitled “Trends in Intake of Energy and macronutrients…”, fat intake decreased in the US from 1971 to 2000.  Proponents of the low fat diets = obesity argument will be quick to jump on this report and say “I told you so.”  But let’s look deeper at this report.  In the same time period in which fat intake decreased in the US, kilocalories from food in general actually INCREASED.  So Americans might have been eating less fat, but they were actually eating more calories, and let’s not forget that they were also very sedentary.  Thus, eating too much and exercising too little is the true cause of obesity being on the rise, not low fat diets.

But the evidence against the low fat = obesity argument does not end with the American and US reports.  Several academic studies have confirmed that low fat diets (as long as they are also lower in calories) can help people to lose weight, while also preventing several deadly diseases such as heart attacks, stroke, and certain types of cancer.  when these studies have not directly said this, they have debunked the myth of this argument by explaining that sedentary and inactive lifestyles contribute to obesity rather than the low fat diets.  Studies like these have appeared in the International Journal of Obesity, Science, The Journal of Clinical Endocrinology and Metabolism, Obesity Reviews, and Archives of Internal Medicine, to name a few.  See below for a list of links to the abstracts of some of these articles.

So, there you have it.  Low fat diets do not contribute to obesity.  Am I suggesting that you then adopt a low fat diet, because it will help you to lose weight?  Not necessarily.  I am suggesting that you increase your activity level and decrease your calorie intake if you wish to lose weight.  Inactivity has been shown again and again to be contributing to the obesity epidemic.  Overeating (no matter where the calories are coming from) has also been show to contribute to weight gain.  If you are overeating fat, then sure, decrease your fat intake.  How do you know if you’re overdoing it?  Get a nutritional analysis, which you can get from any Registered Dietitian.  Finally, keep in mind that fats contain 9 calories per gram, whereas protein and carbohydrates contain only 4 calories per gram.  So it is only natural that if you’re overdoing it on the fat intake, decreasing it would also decrease your overall calorie intake.

Proponents of low-carb diets (which are often high in fat) will now likely argue that low-carb diets “work,” so people should just go ahead and eat a high fat diet.  I will write more on low carb diets later; however, I do want to address one point: people lose fat on low-carb diets for two reasons: 1. Low carb diets tend to be lower in calories.  Eating less calories helps with weight loss, as I have addressed previously.  Thus, it’s not the low carbs that are helping, it’s the low caloric intake.  2. People lose a lot of water weight when they first start on a low-carb diet, whereas what you should really be trying to lose is body fat.

So, the point I’m trying to make is this, and I quote my sister Tina, a dietitian: “reality is that any diet can cause obesity… when you eliminate calories from one source (fat in this case), you can sometimes make up with others, like carbs, which in excess are stored as fat… so the bottom line is that a diet that truly reduces calorie intake (either from fat, or any other combination of sources) would not cause obesity.”

The true way to lose weight is to increase your activity and decrease your calorie intake (no matter what the source).  Furthermore, high fat consumption, especially saturated fat, has been shown to be linked to several deadly diseases.  So my advice is… eat sensibly, exercise, and forget the “experts” who are telling you what to eat.  Eat what you enjoy, but do it in moderation, and choose physical activities that you enjoy and therefore will continue doing for life.

I can just anticipate all the “grain-free/gluten-free gurus” showering down on this post about how grains are bad for you.  I will be writing more about grain free diets very soon, so stay tuned.

Please see below for a list of some academic articles on low fat versus obesity (ap0logies in advance for not listing the titles in APA style; no time.  Check the links for the proper citations):

The role of dietary fat in the prevention and treatment of obesity.  Efficacy and safety of low fat diets


Environmental Contributions to the Obesity Epidemic


A Randomized Trial Comparing a Very Low Carbohydrate Diet and a Calorie-Restricted Low Fat Diet on Body Weight and Cardiovascular Risk Factors in Healthy Women


The role of low-fat diets in body weight control: a meta-analysis of ad libitum dietary intervention studies


Should we recommend low fat diets for obesity?


Effects of low carbohydrate diets versus low fat diets on weight loss and cardiovascular risk factors


Trends in Intake of Energy and Macronutrients – United States 1971-2000


Canadian Consumer Trends in Obesity and Food Consumption



Walking in my clients’ shoes update:

So I’ve been a bad, bad girl this week.  The nasty cold that’s been going around in K-town made its way through the house.  Sick baby, sick toddler, sick daddy, and sick mommy, plus still continuing full time work and studying for my Certified Exercise Physiologist certification = a very big hit on my workout routine.  The S/I joint pain also returned with a vengeance in the beginning of the week.  So now I need to get better at doing my physio again daily.  This week has been a bit better and I hope to have better news about how the training is going during the next post.  But the good news is that I finally got my swimming membership and tri-training can now really begin! Excited for this year’s races and I’ll keep everyone posted.

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