Your microbiome, metabolism, and failure to achieve permanent weight loss

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By now most people are 10 days in to their annual New Years Resolution weight loss program.  They’re hitting the gym, cutting the calories, and making a concerted effort to get back on track after a month and a half of eating like a lunatic.

Of course, as someone in the fitness industry, I get a front row seat at how all of this pans out.  And in a few months some people will be a few pants sizes smaller, but the vast majority will be right back where they were.

This isn’t to say that some people won’t see some level of success.  You may end March 15-20lbs lighter than you were on January 1st, but this isn’t a good way to gauge success.  What good is being down 20 lbs in March if you manage to put it all back on and more by December?

Some of this has to do with your approach.  Trying to successfully manage your weight for only 3 months out of the year would be like trying to become a doctor with 2 years of schooling: it just doesn’t work.  Weight management is an ongoing process that never ends.

However, there are some physiological reason why your December binge will all but set you up for failure.  The 2 primary reasons are:

  • Your starvation diet during the first 3 months of the year slows your metabolism for the rest of the year
  • Your binge in December changes your microbiome and makes weight loss more difficult once you clean up your diet.

Although there’s no direct science linking these 2 specifically to one another for New Years Resolutioners, I’m almost certain they’re linked for this population.  Let’s dig in to the science.

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Reducing caloric intake and metabolism

There’s no controversy on how reducing your caloric intake affects your metabolism.  When you cut your calories your resting metabolic rate drops, it’s as simple as that.

Resting metabolic rate is the amount of calories your body burns just being alive.  Basically, if you laid in bed and did nothing, your body would still burn calories and this is your resting metabolic rate.

The total number of calories you burn in a day is determined by 3 things.

  • Resting metabolic rate(RMR)
  • Physical activity
  • Thermic effect of food

By far, the largest contributor to your daily energy expenditure comes from your resting metabolic rate.  Of course, this changes as you increase the amount of exercise you do, but unless you’re running marathons, your RMR dominates the pack.

Many people attempt to manipulate the thermic effect of food which is a complete waste of time.  The thermic effect of food is the amount of energy needed to process the food you eat. It’s basically the metabolic cost of digestion.

Many have incorrectly taken this information and used it to encourage people to eat smaller meals more frequently.  The myth goes, “If you eat every 3 hours, you’ll keep your metabolism going.”

The problem is, this will have absolutely no effect on the total number of calories you burn from the thermic effect of food.  That’s determined by how much you eat, not how often.  So, anyone who cuts the total number of calories they eat in a day will be cutting the contribution of the thermic effect of food whether they eat 2 times a day or 50 times a day.

So, in effect, cutting your calories decreases 2 of the 3 contributors to your daily energy expenditure.  And this effect isn’t temporary.

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Very low calorie diets: 12 months later

Depending on how much you cut your calories, your body adapts by decreasing your metabolic rate.  In a study comparing a very low calorie diet(500cals/day) to a moderate calorie diet(1200cals/day), those eating a very low calorie diet saw their metabolism drop by 17%.  The moderate calorie diet showed no change in metabolic rate(1).

Another study found that those who undertook a very low calorie diet experienced metabolic changes that lasted for a year or more(2).  The very low calorie diet induced changes in hormones that regulate both appetite and metabolism.

The implications from very low calorie diets are pretty straightforward.  Beginning in January, you starve yourself for 3 months.  When December rolls around your metabolism is slower than it was the previous year.  Your appetite is also dysregulated so you indulge more than you did during the previous holidays.  Now you’r 5lbs heavier than last year.

You’ve gauged your success on comparing your weight in January to your weight in March.  The problem is, your weight the following January is higher than it was the year before.  But, there’s more…

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Your holiday binge trashed your microbiome

Another important factor, one that’s probably linked to your drop in metabolism, is how your holiday binge affected your microbiome.  A new study in mice took a look at how previous diet affects the success of a newly implemented diet.

Researchers took microbiome samples from 2 groups of people that eat drastically different diets.  The first group ate a standard American diet that’s not unlike what you’d do during the month of December.

The second group practice something called the CRON diet.  CRON stands for Calorie-Restricted Optimal Nutrition.  These people eat a very clean diet that’s both nutrient dense and 20% lower in calories than they need…and have done so for a very long time.

Looking at their microbiome uncovered some species of bacteria that are associated with each type of diet.  Most of these bacteria were members of the bacteriodetes phylum.  This becomes important later on.

The CRON microbiome also had greater diversity than the American diet microbiome.  These microbial signatures were then introduced to mice to identify differences between responses to the 2 diets.

In the mice who were given the microbes from the standard American diet, the response to the CRON diet was blunted.  In other words, the mice that had the microbiome associated with the CRON diet responded immediately to it and had better results.  The mice with the microbiome associated with the standard American diet took longer to respond to the CRON diet and did not have the same level of success as the CRON microbiome mice(3).

To determine whether this was specifically related to the microbiome, researchers co-housed the mice together.  Co-housing the mice causes microbial transfer because mice eat the poo of other mice.  When the American diet mice were co-housed with mice given the CRON associated microbiome, their response to the CRON diet improved(3).

The results of this study imply that a 4-6 week binge during the holidays blunts your response to the diet you begin on January 1st.  This coupled with the year-long change in appetite and metabolism caused by your diet last year show how this cycle of binge-diet-binge year after year leads to poor weight loss success over the long-term.

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My experience

For the most part, I tend to let a little loose during the holidays just like everyone else.  If there’s any difference between the general population and myself it’s that I don’t stop exercising during the holidays.  I can tell you unequivocally that my clients dramatically slash the amount of exercise they do in December by at least 50%.

Even though I keep exercising, I do gain a bit of weight during the holidays.  In years past, I typically gained 10lbs during the month of December and this year was not drastically  different.  Usually, this weight takes a month to take off.

In August I developed and implemented a program to increase the diversity of my microbiome.  If you want to check out that journey go here.  Last November my microbial diversity was in the 3rd percentile and this year, as of October, my microbial diversity was in the 42nd percentile.  My firmicutes:bacteroidetes ratio also flipped from 4.9:1 to 0.6:1.

This year my December weight gain is already off in 6 days.  Of course there’s no way that was all fat.  Chances are, a lot of the weight gain was water which is much easier to take off.  Maybe my newfound bacteroidetes and microbial diversity protected me from actual fat gain.

I attribute my previous poor diversity to my C-section birth, formula feeding, and years of rampant antibiotic use in my youth.  Research indicates that the use of antibiotics early in life predisposes to obesity later(4).

There appears to be significant consequences to antibiotic use, many of which affect host metabolism over the long-term.  I think I fit in to that group as I’m definitely prone to weight gain and high blood glucose.  Right after college my weight was 215lbs and it climbed to as high as 243lbs at one point.  I maintained a weight of 215lbs+ for 10 years.  I’m currently 190lbs and on the way down.

Ironically, I took a week-long course of doxycycline last December and decided to perform Ubiome tests before, during and after to assess the impact of antibiotics on my microbiome.  Since my diversity pre-antibiotic was only in the 3rd percentile, there’s no way to tell if taking them reduced my already terrible diversity.  My initial goal was to see if I could rescue my microbiome with fiber and probiotics…that approach didn’t work.

Once I changed my approach to improving microbial diversity I saw excellent results.  To do this I had to widen my approach.  Rather than focus on fiber and probiotics in the diet, I focused on dietary factors that influence bile flow and digestion.  I also had to work on meal timing, type of exercise, and stress management.  This improved my diversity and increased my  bacteriodetes numbers.

We’ll see if it translates to sustained success.  Ideally I’d like to be 5lbs less than I am now which would put me at 185lbs.  I was within 2lbs of that goal right before Thanksgiving without having to be overly strict on my diet.

My all-time post-college low was 172lbs 3 years ago on a very strict low-carb Paleo approach.  If I can get to 185lbs without having to be overly strict on my diet I’d be more than satisfied.  At this point in my life, I have no desire to cut craft beer, carbs, and all processed food out of my diet for 3 months like I did 3 years ago.  Even then, it would come back on once I stopped doing that.

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There are a number of factors working against you when you take the standard New Years Resolution approach to weight loss.  If you took the same approach last year, you’re likely dealing with some residual metabolic derangement that affects both metabolism and appetite.  This will help you pack on a couple more pounds and make your job much more difficult than it needs to be.

Another factor is your diet leading up to your resolution.  If you spent the entire period between Thanksgiving and New Years eating like a monster, your microbiome may shift in a way that delays progress.  A person eating a sensible diet during the holidays not only has the help of their microbiome, they don’t have a big hole to dig themselves out of.

But there is an alternative.  Unfortunately that alternative would involve  eating skinny mouse poop…I’ll pass.  All joking aside, if you have it in your head probiotics are going to help you they’re not.  At least not until your gut is in the proper condition for their growth.


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