Just How Much (And For How Long) Does Metabolism Slow Down After Weight Loss?

Many people who struggle with excess weight find that they are able to get weight off, but keeping it off seems next to impossible.

So what exactly happens to our metabolism when we lose weight?  And are any changes in our metabolism temporary, or there for the long term?

A very elegant study was conducted that answers this question – and you may be surprised by the results.

The study enrolled people in groups of three, all three of which were of the same gender and weight: one who was weight stable at their maximum lifetime weight (ie had not had any weight loss); one who had lost at least 10% of body weight and kept it off for at least a year; and one who lost at least 10% of body weight over the most recent 5-8 weeks (using a liquid diet for 1-2 months before the study testing was performed).  The average body weight of people in the study was 98 kg (216 lb), and the age range was 19-41 years. All participants lived at the research centre for the duration of the study, and were fed only a liquid formula diet, to ensure their weights were stable for at least 2 weeks before measurements of metabolism were taken.  (a very impressive and dedicated protocol for both participants and investigators, wow!)

They found that in these study participants, the 24h calorie burn was about 450 calories lower for the people who had previously lost weight, regardless of whether that weight loss was just weeks ago, or whether it was years ago (and similar for males and females in the study).  Many full meals come in under 450 calories - I googled this recipe website to give you an idea (though I have not reviewed the recipes per se).  So this means that the person who has lost weight has to eat this much less, EVERY DAY, for years (and possibly forever) in order to maintain that body weight, compared to someone who weighs the same but has never weighed more than that.

Here's an example from that website: it's a lot of food!

While this 450 calorie drop in 24h calorie burn was partly due to a drop in energy burn at rest, the biggest drop was seen in the energy burned by activity (called non-resting energy expenditure). (Read more about all components of daily energy expenditure here). 

So does this mean that people who have lost weight simply exercise less?  No.  Actually, the literature overall suggests that it is energy burn during low-grade activity that declines (ie activities of daily living), because our muscles become more efficient at low levels of physical activity with weight loss. 

So what can you do to combat this reduction in energy burn that happens with weight loss?  Two things.

1.  Be NEAT! NEAT, or non exercise activity thermogenesis, is low grade activity of daily life.  Give up your parking pass and take public transit (which involves more physical activity than driving). If you do drive, park at the far end of the parking lot.  Stand while you talk on the phone.  Take the stairs instead of the elevator.   Read more on NEAT here!

2.  Exercise more.  Easier said than done, and not all may be able to do this because of physical limitations - but it is because of this drop in metabolism that the US Obesity Guidelines recommend more moderate physical activity to prevent weight gain (200-300 mins per week) than they do for weight loss (150 mins per week).  We have only to look at the National Control Weight Registry to see the proof – 90% of Americans who have lost 30 lbs or more, and kept it off for more than a year, exercise for at least an hour each day.

***Be sure to talk to your doctor before starting or ramping up your exercise program, and also to help you find assistance to learn about modified exercises that may work for you if you have physical limitations.***

Follow me on twitter! @drsuepedersen

www.drsue.ca © 2016

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Liraglutide Reduces Heart Disease In People with Type 2 Diabetes

BIG news in the diabetes world was released on Friday - for the first time, a medication in the class called GLP-1 receptor agonists, called liraglutide (trade name Victoza), has been shown to reduce cardiovascular events in people with type 2 diabetes.

The LEADER trial enrolled over 9000 people with type 2 diabetes, who were at high risk of cardiovascular disease, and randomized them to receive either Victoza vs placebo with usual standard of care.

They found that Victoza was better than placebo to reduce the combination of death from cardiovascular disease, non-fatal heart attack and non-fatal stroke. A reduction in all three of these components contributed to the benefit that was seen.   The numbers and details are not yet available - we'll have to wait until the American Diabetes Association meeting in June to find out more.

Here's why this is ground-breaking news: 

We have long been uncertain whether we are actually preventing cardiovascular disease by treating diabetes - we know that the higher sugars are, the higher the risk of heart disease, but it has been evasive to actually prove that lowering blood sugars prevents heart disease. The next question is whether some medications to treat type 2 diabetes could be better (or worse) than others to protect from heart disease.  LEADER has now shown us that treating type 2 diabetes with liraglutide does indeed protect patients from cardiovascular events.

Within the GLP1 receptor agonist group of medications, a study of lixisenatide (called the ELIXA study) showed that it did not increase the risk of cardiovascular events, but it didn't prevent them either.  Studies of the other GLP1 receptor agonists available are currently underway.

As far as other type 2 diabetes medications go, the only other medication that has clearly been shown to reduce cardiovascular disease is empagliflozin, which you can read more about here and here.  Metformin, which is the #1 treatment advised for type 2 diabetes worldwide, has some weak evidence that it prevents cardiovascular events as well.

We will be waiting in anticipation for more details from the LEADER trial in June!


Disclaimer: I have been involved in research trials of liraglutide.  I receive honoraria as a continuing medical education speaker and consultant from the makers of liraglutide (Novo Nordisk). I am involved in research of medications similar to liraglutide for the treatment of type 2 diabetes.

Follow me on twitter! @drsuepedersen

www.drsue.ca © 2016

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The Legacy Effect 30 Years Later - Good Control of Diabetes Prevents Heart Disease

A lot of people with diabetes wonder why their doctors and diabetes educators are seemingly obsessed with keeping blood sugars as close to normal as we can.  After all, blood sugars that are only mildly elevated usually don't come with much in the way of symptoms.

The point to keeping sugars as well controlled as possible is to prevent complications of diabetes developing over time - this includes damage to the eyes, heart, kidneys, and nerves in the feet and elsewhere in the body.

And - a new paper published has now shown us that the benefit of good control of diabetes to prevent cardiovascular disease persists for at least thirty years!

The study, which was recently published in the journal Diabetes Care, evaluated patients 30 years after their initial participation in the famed (well, famous in the diabetes world anyway) DCCT trial.  This was a clinical trial that enrolled 1,441 patients with type 1 diabetes, and assigned them to receive either more intense, or less intense, control of their blood sugars for a mean of 6.5 years.

During the 30 years of follow up, they found that the people who were in the tightly controlled group 30 years previously had a 30% reduction in the risk of developing cardiovascular disease, and a 32% reduction in the likelihood of having a heart attack, stroke, or dying from a cardiovascular cause, compared to those who were in the less tightly controlled group.  The tighter blood sugar control during the time of the original 6.5 year study was statistically responsible for all of the difference in cardiovascular disease between the two groups.

This data really impresses upon us the power of what we call the 'legacy effect' - good control of diabetes early on prevents complications later in life.  (Note: there is a similar trial in type 2 diabetics called the UKPDS study, which also showed that the legacy effect exists 10 years later.)

I think it is challenging for anyone to look forward 30 years into the future, and think about the importance of what we are doing now to our future self.  If you think about it, we actually spend a lot of our lives planning for our 30+ year future self.  Take financial planning, for example - most of us structure our home purchases, savings structures, and investments with the goal of planning for the distant future.  As I see it, planning for our health in the future is no different - and for people with type 1 diabetes, we now have very long term data to back this up.

Follow me on twitter! @drsuepedersen

www.drsue.ca © 2016

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Natural Remedy Star Fruit Causes Kidney Damage

It is often in my day that people tell me that they are taking natural remedies for any number of medical conditions - for aches and pains, diabetes, obesity, cancer prevention... the list goes on.  The thinking that often underlies the decision to take these remedies is that they are natural, so how could they possibly be harmful?

I worry about my patients taking natural or naturopathic products, because rigorous clinical trials are not done to show benefit, nor (most concerning) to understand potential harms.  So, when I came across two very serious case reports of kidney damage from the seemingly innocent star fruit, I wanted to share it to illustrate the potential dangers of natural remedies.

Star fruit comes from a tree native to India and southeast Asia.  In addition to eating them as a fruit (I've enjoyed them myself on occasion while traveling to these areas), they are also touted as a herbal remedy for various ailments (including diabetes) in these countries.

Recently, two cases of star fruit toxicity were published.  One case was that of a woman with type 2 diabetes who consumed 200 mL of star fruit juice (less than a cup) from six star fruits, which resulted in kidney failure due to an inflammatory reaction in the kidneys (acute interstitial nephritis) caused by the high oxalate content of star fruit.  Thankfully, with medical treatment, her kidneys recovered.

The second case was that of a man with a history of moderate kidney dysfunction, who developed kidney failure after eating four star fruits over four days.  Thankfully, he also recovered after about 2 weeks.

In addition, like the grapefruit, star fruit also inhibits a group of liver enzymes (cytochrome P450 isoforms) which are important for metabolism of medications such as statins (cholesterol medications).  This is why it is advised for patients on statins not to eat grapefruit - star fruit should be included in this counselling as well.

So, take these cases into consideration the next time you think about reaching for a herbal remedy - remember that we simply do not know enough about these remedies to know if they are safe.

As a patient, be sure to tell your doctor about any natural remedies you are taking.

As a health care professional - remember to ask.

Follow me on twitter! @drsuepedersen

www.drsue.ca © 2016

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PREdiabetes May Cause Kidney Damage

In our quest to control blood sugars of people who have diabetes, one of the 'small blood vessel' complications of diabetes that we are trying to prevent is damage to the kidneys.  For people who have prediabetes, it has generally been thought that they do not have an increased risk of small vessel disease.  However, there is mounting evidence that prediabetes may in fact cause small vessel damage; a new study suggests that prediabetes may in fact cause kidney damage.

First, let's talk about what we mean when we say 'prediabetes'.  Diabetes and prediabetes are defined on the basis of how high blood sugars are.   Quite simply, prediabetic blood sugars are lower than diabetic range blood sugars, but higher than normal blood sugars.  For the exact blood sugar definitions in Canada, please see Table 2 (diabetes) and Table 4 (prediabetes) here.

A study suggesting that prediabetes causes kidney damage was published in the American Journal of Kidney Diseases.  The study was a prospective cohort study that followed 1,261 people without diabetes between the ages of 50-62 for a median time of 5.6 years.  Participants who had prediabetes at the start of the study were at nearly 2 times higher risk of having hyperfiltration (an early manifestation of diabetic kidney disease), and at 1.8 times higher risk of having higher-normal albumin levels in their urine, compared to those with normal blood sugars (albumin in the urine is also a diabetes-related kidney complication). These changes were seen independently of other risk factors such as blood pressure at baseline, and independent of changes in blood pressure medications.

That prediabetes can cause complications before diabetes develops has a profound impact, in that 1 in 4 Canadian adults has diabetes or prediabetes, with most of those being prediabetic.  (In USA, 44% of American adults have diabetes or prediabetes).  Most people with prediabetes do not know that they have this condition, as there are usually no symptoms of this condition.

While the notion that prediabetes can cause small blood vessel complications is relatively new, it is known that prediabetes (especially impaired glucose tolerance) are at a substantially higher risk of developing BIG vessel complications (eg heart disease).

Knowing that prediabetes can cause organ damage makes two things very clear:

1.  We need to be checking for prediabetes in people who are at risk; and

2.   We need to aggressively prevent and treat prediabetes.

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www.drsue.ca © 2016

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Part 2 - Why It Is So Hard To Avoid Weight Regain

In last week's post, I talked about the decrease in energy burn that happens with weight loss.  Today, let's focus on the other major driver of weight regain - the powerful changes in hormones that happen with weight loss, which drive us to eat more and regain the weight we worked so hard to lose.


In humans, there is only one hormone that is known to increase hunger, called ghrelin.  Interestingly, there are many hormones that signal satiety, telling us that we feel full.  Several hormones tell us we feel full in the short term (release 10-15 minutes into a meal), including hormones called GLP-1, cholecystokinin (CCK), PYY, oxyntomodulin, and others.  There are also hormones circulating that are long terms signals of fat and energy storage, which are also fullness hormones: leptin, which is made by fat cells, and insulin, which is made by the pancreas.  These hormones act in the hypothalamus in our brain to regulate when and how much we eat.  (there are also many emotional and social drivers of eating, called 'hedonic' mechanisms... stay tuned for more on this important factor another day :).


When we lose weight, leptin and insulin both drop precipitously, which result in a powerful drive to eat and regain the lost weight.  The short terms regulators of hunger and fullness are affected as well, including a decrease in GLP-1, PYY, and CCK, and an increase in ghrelin, all of which work in concert to beg our brains to eat more, eat more!  Studies have shown that even a year after weight loss, these hormone changes persist - an unrelenting drive to regain the lost weight.

So what can we do to combat these hormonal changes?  It's not easy - evolution has made it so to drive us HARD to look for food and eat during times of food scarcity.  Keeping the energy burn up with activity helps to offset the powerful hormonal drive to increase energy intake, but a whole lotta exercise can be 'cancelled out' by what we can eat in just a minute or two.  Fortunately, medications are now available or in development to combat these hormonal changes, which can help to maintain weight after weight loss.  The only medication along these lines available in Canada is called liraglutide or Saxenda, and it has been shown not only to help people to maintain an average 6% weight lost from diet and exercise, but actually helped people lose an additional 6% weight loss over a year on top of that (with the ever critical lifestyle changes continued throughout).


Disclaimer: I was involved in the research trials of liraglutide as an obesity treatment.  I receive honoraria as a continuing medical education speaker and consultant from the makers of liraglutide (Novo Nordisk). I am involved in research of medications similar to liraglutide for the treatment of obesity and type 2 diabetes.

Follow me on twitter! @drsuepedersen

www.drsue.ca © 2015 

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Why Is It So Hard To Avoid Weight Regain?

One of the biggest challenges in successful weight management is prevention of weight regain after weight loss.   Studies show that most often, people regain weight after intentional weight loss, with many people regaining most or all of their lost weight over time (and then some, in some cases).

There are two major drivers of weight regain:

1.  Many powerful changes in hunger and fullness hormones happen with weight loss, which drive us to eat and regain weight.

2.  Our energy burn (called 'energy expenditure') drops - more than we might expect.

Today, we are going to focus on #2 above. (stay tuned for much more on #1 another day!)


So, just how much does our energy burn drop with weight loss?

Well, it turns out that we are geared towards retaining energy and downregulating metabolism in the face of weight loss, as a strong defence mechanism genetically engineered to protect our weight to survive times of famine.  This happens thanks to a decrease in thyroid hormone levels, decrease in sympathetic nervous system tone, an increase in skeletal muscle efficiency, and other changes as well.  While we do expect a proportional decrease in energy burn simply due to the weight loss itself, the decrease in energy burn is actually much more than that, thanks to these changes.


Here's an example: When a person loses 10% of their body weight, one might think that their daily energy burn (called Total Energy Expenditure or TEE) would also drop by 10%, reflecting 10% less body mass that needs daily care and energy, and 10% less body mass for the person to physically carry around in a day.  In fact, studies show that the total energy burn of this person will actually drop by 20-25%, - in other words - to 10-15% less than what would be predicted.

Said another way, it will take 300-400 fewer calories per day to maintain the 10% loss in body weight, compared to a person of the same body shape, size, and weight, who hasn't lost 10% of their weight.

This decrease in total energy expenditure may not persist forever - the POUNDS LOST study suggested that the TEE comes back up to expected baseline after 2 years (though others have suggested that the reduced energy burn lasts as long as 7 years or more).   Some research has also suggested that the drop in energy expenditure may be less with a low carb diet, higher with a low glycemic index diet, and the highest on a low fat diet (my speculation on this is that this may be related to higher protein intake in the low carb diet - it takes more calories to burn and digest protein compared to carbs compared to fat).

Because of this reduction in energy burn with weight loss, as well as the powerful hormone changes that happen to drive hunger, it is very difficult to maintain weight loss.  Fortunately, the American National Weight Control Registry has provided some useful information regarding habits that help keep the weight off (though these are not easy either) - check it out!

Follow me on twitter! @drsuepedersen

www.drsue.ca © 2015 

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