What Canada’s new obesity guidelines say about the tricky question of weight loss

What Canada’s new obesity guidelines say about the tricky question of weight loss

What Canada’s new obesity guidelines say about the tricky question of weight loss

The updated Canadian Adult Obesity Clinical Practice Guidelines were published August 4, replacing the 2006 version. They’ve been praised for being the first guidelines to acknowledge the problems of weight stigma and bias, and for shifting the emphasis from weight to health. Since I’ve been practicing that way for years now, I was curious to see the detailed recommendations.

(I should say, before jumping into this, that I wish I could avoid using the “o” word in this post. I know some people find it offensive, but the medical community continues to use it, so if I’m going to talk about this topic, I can’t really get around it. It’s been redefined, by the way. More on that in the endnote* if you’re curious.)

Anyhow, the advice regarding weight loss in the guidelines is anything but straightforward, but that’s par for the course. Obesity is complex and everybody is different. There are no simple answers.

The gist of it is (1) health matters most (2) weight loss may help in some cases but (3) if you manage it, there’s a good chance you’ll gain it back, and that’s not your fault: Our bodies are finely-tuned weight-loss resisting marvels.

The document is available online and each chapter has key messages for both providers and people “living with obesity.” So if you want to see for yourself, take a peek! But here’s my take on it.

Key message: Health matters most

This message comes through loud and clear, starting with the heading of the press release:

New Canadian Adult Obesity Clinical Practice Guidelines Published: Treatment Goals Are Improved Health And Quality Of Life, Not A Number On A Scale.

The summary article in the Canadian Medical Association Journal (CMAJ), which is all many clinicians will likely read,  echoes this sentiment, starting right in the introduction:

There is a recognition that obesity management should be about improved health and well-being, and not just weight loss.

From the widely-praised chapter on reducing weight bias:

Try focusing on improving healthy habits and quality of life rather than weight loss. Weight is not a behaviour and should not be a target for behaviour change.

Wow! This is revolutionary stuff. Continuing on, from the nutrition chapter:

Nutrition interventions for obesity management should focus on achieving health outcomes for chronic disease risk reduction and quality of life improvements, not just weight changes.

And in the physical activity chapter:

Weight loss should not be the sole outcome by which the success of physical activity therapy is judged.

The perspective continues throughout. I love it.

Weight loss is still a major theme

However, all this health-first messaging is layered on top of the assumption that weight is still the focus. In the summary article, we see it as soon as the topic shifts to treatments. It starts out weight-neutral:

All individuals, regardless of body size or composition, would benefit from adopting a healthy, well-balanced eating pattern and engaging in regular physical activity

but then reports:

Aerobic activity (30–60 min) on most days of the week can lead to a small amount of weight and fat loss, improvement in cardiometabolic parameters, and weight maintenance after weight loss.

Studies do show that. For the record, the weight loss works out to about 2 kg, on average, according to the physical activity chapter, just so we’re clear. Of course it will be more for some people, less for others.

Regarding nutrition therapy, they go on to say:

Weight loss and weight-loss maintenance require a long-term reduction in caloric intake.

References to weight management continue throughout the summary and most of the individual chapters. Many of the recommendations are either suggestions to lose weight or prevent weight gain with certain conditions, or guidance on how to do it.

In “The Science of Obesity” chapter, there is a whole section on the “Benefits of modest weight loss.” (Little discussion of potential harms, unfortunately.)

The pharmacotherapy chapter is pretty much all about how medications can help with weight loss:

Pharmacotherapy augments the magnitude of weight loss beyond that which health behaviour changes can achieve alone and is important in the prevention of weight regain.

The number one recommendation in the “Commercial Products and Programs in Obesity Management” chapter highlights which commercial programs “should achieve mild to moderate weight loss over the short or medium-term.”

I could go on, but I think you get the idea.

How to make sense of the apparently mixed messages?

I’ve literally been losing sleep trying to figure out how to reconcile this.

Part of the problem is that most research into improving the health of people living with obesity has been done on weight loss, presuming that was the answer. The guideline summary article says as much:

“Because the existing literature is based mainly on weight-loss outcomes, several recommendations in this guideline are weight-loss centred. However, more research is needed to shift the focus of obesity management toward improving patient-centred health outcomes, rather than weight loss alone.”

And if you read the health-first statements carefully, it’s usually not framed as health instead of weight loss, it’s both. For example, from the summary:

“This guideline update … shifts the focus of obesity management toward improving patient-centred health outcomes, rather than weight loss alone.”

We also see a lot of the word “just,” as in:

There is a recognition that obesity management should be about improved health and well-being, and not just weight loss.

So weight loss isn’t gone, it’s just seen as a means to an end, at least for some people. Major paradigm shifts don’t come easily.

But is weight loss the path to better health?

Welcome to the great debate of our time in our profession: Can people actually lose weight and does that improve health and wellbeing in the long run? We really can’t say for sure. Some will say absolutely yes, and some will say definitely no. There are pros, well described in these guidelines, and there are cons, as outlined in this paper.

The pros win the day with guideline authors, because they’ve been demonstrated in high-quality studies, although those are mostly short-term in nature (1-2 years): Improved blood pressure, blood sugar control, mobility, and more.

The cons have not, in part because they take longer to occur, and funding for studies like this is harder to get. As we read in the nutrition chapter:

Most studies with a nutrition component were short- to medium-term interventions, limiting our knowledge of long-term outcomes.

There are also a couple of hints in the nutrition chapter that dieting may promote long-term weight gain, but that’s about it for a discussion of the downsides.

…weight loss or weight cycling can lead to biological compensatory mechanisms that can promote long-term weight gain in some people.

Acknowledgement that weight lost is usually regained

With that, at least, there are numerous references to the reluctance of the human body to shrink. I’m so glad to see this! Far too many people have been blamed (or blamed themselves) when the scale didn’t comply despite diligent efforts. Hopefully this will help to chip away at some of the weight bias and stigma out there.

From the nutrition chapter:

“…weight loss may not be sustainable long-term, not because of personal choices or lack of willpower, but rather from strong biological or physiological mechanisms that protect the body against weight loss

Read that again. “Not because of personal choices or lack of willpower.” Hallelujah.

And further explanation:

Although a caloric deficit is required to initiate weight loss, sustaining lost weight may be difficult long term due to compensatory mechanisms that promote positive calorie intake by increasing hunger and the drive to eat.

Compensatory mechanisms, as in your body trying to save you from starvation.

And how long before lost weight comes back? There’s no clear answer on this one, but, again from the nutrition chapter:

Caloric restriction can achieve short-term reductions in weight (i.e.< 12 months) but has not shown to be sustainable long-term (i.e. > 12 months).”

I’m also glad to see this acknowledged because people considering weight loss deserve realistic expectations.

And how much weight can you lose?

As well, we owe people an honest account of what is achievable. From the summary:

The weight loss achieved with health behavioural changes is usually 3%–5% of body weight, which can result in meaningful improvement in obesity-related comorbidities. The amount of weight loss varies substantially among individuals, depending on biological and psychosocial factors and not simply on individual effort.

Again, another one to pause and really read. What does 3-5% look like for you? Take a second to do the math. Probably a smaller number than you were hoping for. As they say though, even that might result in some health improvements, at least temporarily, until you gain the weight back.

Mind you, this is just from “health behavioural changes,” primarily dieting and exercise. What most people try. Other interventions are recommended in the guidelines though (see below), and they’ll likely take you a bit further.

While you’re re-reading, consider the statement: “The amount of weight loss varies substantially.” That means you and your friend can try the same diet and he may lose 20 pounds (at least for a while) while your weight hardly budges. Not your fault! Everybody is unique.

You might be thinking, “I know a guy who lost a lot more weight than that.” Or maybe you have done it yourself. But I’m not talking about how much weight a person loses after six months or even a year of trying. I’m talking about what happens to them after that. And years later. If/when that weight comes back, what happens to their self-esteem, confidence, commitment to proven health behaviours, relationship with food, and of course, their long-term health?

At least if people go into it with realistic expectations, they’ll be less likely to feel ashamed if things don’t work out quite like they’d hoped.

What does it really take to lose weight?

Our best long-term study of what it takes to lose weight right now, short of surgery, is the landmark LookAHEAD trial, discussed in the guidelines. After eight years, the people in the intensive intervention group lost an average of 4.7% of their initial weight, with about half of them keeping more than 5% off.

The weight loss looked like this.

(DSE = diabetes support and education, ILI = intensive lifestyle intervention.)

Notice how weight loss is maximal about a year into the study, but then starts to decrease. This is typical for a weight loss study, although unusual in that people kept more off for longer.

How did they do it? “Intensive” is the key word. This is what was involved:

  • 42 meetings (!) in the first year with an “experienced interventionist” (registered dietitian, psychologist, or exercise specialist, sometimes alone, sometimes in a group), and then monthly meetings thereafter, for help with goal setting and problem solving,
  • at least 175 minutes a week of moderate-intensity physical activity,
  • replacement of ideally two meals and one snack daily with diet shakes and bars (eg. Slimfast), which were provided free of charge (not everyone used that many, but those who used more lost more),
  • following structured, reduced-calorie meal plans, which were also provided,
  • regular recording of food eaten,
  • weight loss medication (also provided), if needed.

My question is, do you have this much support? Do you have these resources at your disposal? Do you have the time for all of this? Do you want to spend this much of your life this way?

If yes, then you too have a 50/50 chance of meeting what is likely your physician’s suggested low-ball weight loss goal (5%).

Some people are willing and able to put forth that kind of effort. Some not so much. Either way is okay. It’s your choice.

I just think that before we go suggesting patients lose 5-10% of their weight, which health professionals do all the time, we owe them full disclosure of the herculean effort and extensive support involved.

Eating less and moving more isn’t enough

The guidelines also tell us that losing more than the typical 3-5% will likely take more than the oft-maligned “eat less, move more” strategy. Psychological, pharmacologic, and/or surgical treatments are specifically recommended to complement nutrition therapy. From the summary:

If further weight loss is needed to improve health and well-being beyond what can be achieved with behavioural modification, then more intensive pharmacologic and surgical therapeutic options can be considered.

Weight loss medications and surgery might sound extreme, but for some, the benefits may outweigh the downsides. If you think that might be for you, talk to your doctor. The options continue to get better.

And whether you want to go that route or not, the guidelines recommend exploring the “root causes of weight gain and potential barriers to treatment.” I agree: Going on a “diet” will likely be an exercise in futility if you can’t get more than a few hours of sleep a night, for example. Addressing that sleep problem may help and be of great benefit to your health.

Unfortunately, not all contributors to weight gain can be easily fixed. The summary article lists just a few to identify and address if possible:

“…genetics, epigenetics, neurohormonal mechanisms, associated chronic diseases and obesogenic medications, sociocultural practices and beliefs, social determinants of health, built environment, individual life experiences like adverse childhood experiences, and psychological factors such as mood, anxiety, binge-eating disorder, attention-deficit/hyperactivity disorder, self-worth and identity.”

Simple, right?

Benefits of weight loss

And the health benefits? The original goal of the LookAHEAD trial was to show that weight loss helps people with type 2 diabetes have fewer heart problems, but surprisingly, that wasn’t seen:

The intensive lifestyle intervention group did not achieve significant reductions in the rate of cardiovascular events.

I remember that was quite a shocker at the time.

However, they did achieve other health benefits, including improved fitness, better blood sugar control with fewer medications, physical mobility maintenance, and quality of life, as well as decreased rates of sleep apnea, severe diabetic chronic kidney disease and retinopathy, depression, sexual dysfunction, and urinary incontinence. Other studies have demonstrated similar benefits, which is one reason this whole pursuit is tough to give up.

Is there another way?

Perhaps. Non-diet approaches to health are becoming more popular, and they’re actually addressed in the guidelines! That’s revolutionary stuff. Just one short discussion though, and they warn, “There was limited evidence for non-dieting approaches.” Fair enough.

What did they find? From the nutrition chapter:

A systematic review and meta-analysis compared weight-neutral approaches to weight-loss interventions found no significant differences in weight loss, BMI changes, cardio-metabolic outcomes (including blood pressure, glycemic control, lipid profile) or self-reported depression, self-esteem, quality of life or diet quality.

Wow. Isn’t that something? Weight-loss interventions didn’t produce more weight loss or improve cardiac risk factors more than weight-neutral ones?

Could there be any benefits of going this route? One review cited found that a Health at Every Size (HAES®) approach:

improved quality of life and psychological outcomes (general well-being, body image perceptions) with mixed results for cardiovascular outcomes (blood lipids, blood pressure), body weight, physical activity, cognitive restraint and eating behaviours.”

For non-diet approaches in general, we’re told that they:

“may have less impact on weight stigma and may support health behaviours across all weight spectrums”

Huh. Interesting. Given the increased emphasis on fighting weight stigma, you’d think that would have had more impact. However, as I mentioned:

“…caution is needed when interpreting results from non-dieting approaches. There are various non-diet interventions reported in literature with a lack of control groups, a high risk of bias in trials, and inconsistent valid tools used to measure outcomes.

Promising, but we still have much to learn.

The real question here is, which path should you take?

You get to decide that, of course, if you haven’t already, hopefully with the support of a knowledgeable and compassionate healthcare team. As the summary article says:

“Health care providers should talk with their patients and agree on realistic expectations, person-centred treatments and sustainable goals for behaviour change and health outcomes.”

(If you want to change those behaviours, I always like to add. Let’s not make an assumption there.)

Clinical practice guidelines are intended as a compass, not a rulebook, and our messy real lives can’t always replicate clinical trials. More formally, from the summary:

Resource limitations and individual patient preferences may make it difficult to put every recommendation into practice

There is actually an acknowledgement throughout the guidelines that weight loss doesn’t have to be the goal for everyone, and this is consistent with guidance we’ve received from Obesity Canada for years. From the Prevention and Harm Reduction of Obesity (Clinical Prevention) chapter:

…depending on the situation, attenu­ating weight gain as opposed to preventing weight gain or achieving weight loss may be a more reasonable goal.

But if you read all of this and still want to pursue weight loss, I certainly don’t blame you. We’ve been told all of our lives that weight loss is the path to better health.

Some people do lose weight, even in the long run. About a quarter of those in the LookAHEAD intensive intervention group kept off 10% or more of their starting weight. Just remember that people who lose weight tend to talk, blog, or be featured in magazine articles more than people who’ve struggled, so anecdotes alone might give us a skewed view of that.

Your best weight

Personally I like the concept of “best weight,” promoted by physicians Arya Sharma and Yoni Freedhoff for years, and featured in the guidelines. That’s the:

“…weight at which the body stabilizes when engaging in healthy behaviours,” which “may not be an “ideal” weight on the BMI scale. Achieving an “ideal” BMI may be very difficult.”

If you’re living the healthiest life you realistically can (or want to) live, then congratulations! You’re at your “best weight.” Now you can focus on your health.

(Or not. That’s not a moral obligation either.)

Where I’ve landed

Personally, after 15 years as a dietitian, working with many people who’ve spent their lives struggling with this, I’ve moved away from supporting weight loss. I’ve heard the stories of far too many who’ve experienced the frustration of weight regain time and again. Smart, knowledgeable, committed people who’ve spent years of their lives and sometimes thousands of dollars, declined meals with friends, or forgone the joy of a favourite food, all to feel like they’ve failed yet again.

The last straw might have been the 68 year-old woman who told me several years ago, “I don’t remember a time in my life that I wasn’t on one diet or another.” Do you want to say that when you’re 68?

If you still think weight loss is the right choice for you, I’m happy to refer you to a colleague. I know several highly skilled, ethical dietitians who see this differently.

My focus is helping people living with heart disease stay alive and living well for longer. The LookAHEAD study showed us that weight loss doesn’t achieve that. The Lyon Diet Heart study demonstrated that a Mediterranean-style eating pattern produces better results in that respect (arguably with less effort). Participants didn’t lose weight in the DASH study, but their blood pressure dropped. These things we can do.

Similarly, with physical activity, there are numerous benefits not tied to weight loss, including (from the physical activity chapter):

  • cardiorespiratory fitness (“associated with reduced risk of chronic disease and all-cause mortality, independent of BMI“)
  • mobility (“In older participants, exercise alone led to better physical function without significant weight loss“)
  • heart disease risk factors including high blood sugars, high blood pressure, and dyslipidemia (noted: “this occurs independently of significant weight loss“).

I’ve often said, health is more about what you do than what you weigh, and I think in that, we’re all in agreement.

Comments? Questions? You can share on Facebook or privately if you prefer.


* The guidelines offer a (relatively) new definition of obesity, as “a prevalent, complex, progressive and relapsing chronic disease characterized by abnormal or excessive body fat (adiposity) that impairs health“. Recall that conventionally, obesity has been defined by have a body mass index (BMI) of 30 or more. Now they propose that BMI be used for screening but not diagnosis (as well as in population-level studies where the new definition isn’t practical). So if someone meets the BMI definition, but has no related health problems, they would be considered not to have obesity.

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