Flex Dieting 101

Back to the Basics

A major part of my job as a personal trainer is making sure my clients are educated on what they need to do inside and outside the gym to improve their health.  A rule of thumb I use when talking about body composition is that 80% of the changes happen in the kitchen.  This means when it comes to aesthetic goals, I can only get my clients 20% of the way there on weights and cardio alone.  When it comes to the other 80%, as a personal trainer, my go to philosophy is flex dieting.  I use the word philosophy precisely because flex dieting encourages a healthy relationship with food that empowers you to bend based on your daily needs rather than holding to a rigorous and exhausting daily battle to stick to the plan.

A plan that allows you to change your eating day to day and still lose weight sounds too good to be true doesn’t it?  Well here’s the catch, there are some rules.

  1. Eat at a 10-20% calorie deficit
  2. Eat one gram protein per pound body weight

And that’s it.  Pretty tricky right?  For those of you that have been following the blog, it may look pretty similar to my dieting experiment from last year.  In that one I ate at a 10% deficit and lost 3lbs off the scale in 4 weeks (with a low point 5lbs down).  Only difference here is that protein requirement.

Why Protein?

If I had such good results from just the calorie restriction, why the protein requirement too?

Short answer: There are too many reasons to count.

If I had to pick the most important one, protein tends to satiate much more than carbs and fats.  This helps with the hunger and cravings that typically come with dieting.  In my experience as a trainer, the biggest stumbling block for clients on a diet comes from the psychological effects.  Reduced caloric intake often cuts twice when it comes to mental health.  The first cut comes from the increased stress caused from hunger.  The majority of my clients (and I could probably even say the majority of people reading this article), have never experienced hunger in their lives.  At least not on a daily basis.  We live in a society where cravings are easy to fill and our brains have grown accustomed to that.  The second cut comes as food acts as a stress reliever for many people.  See the problem here?  Less food causes more mental stress and no more stress eating means no easy source of relief.  Sure there are better (and healthier) ways to deal with stress, but, when it comes to the practical application, the mental stress of a diet is overwhelming for many and is the main reason for failure (or failure to start).  By introducing a high level of protein, we see a reduction in hunger throughout the day.  Sound a little anecdotal?  Well here’s an article that explains the science behind it (1).

Now that’s a pretty good argument right?  Protein makes you eat less.  Protein is good.  Guess what?  There’s more.  Beyond that, there have been countless studies demonstrating the effectiveness of protein on preserving lean body (muscle) mass while at a caloric deficit (23456 to name a few).  When my clients who want to lose weight describe their ideal body, they talk about toned muscles, defined abs, Michelle Obama arms, and less jiggling when they jog.  The core of all these desires is a solid level of lean body mass.  If lean body mass drops too much, bones start to show and we get more skeletal and less swimsuit season.  Beyond appearance, decreased muscle mass and muscle strength poses increased risks of injuries later in life (7) as well as reduced resting metabolic rates which means future weight loss (or maintenance) later in life will require greater effort (8).

If that wasn’t enough to sway you, what if I told you eating protein actually makes you burn more calories?  When you consume food, it doesn’t magically turn into energy.  Your body goes through a digestive process that takes energy to break down the things you eat into things your body can use.  This is called the thermic effect of food.  Out of all the macronutrients, protein has the highest thermic effect with percentages between 20 and 35 (91011).  This means out of all calories you consume, 20-35% of the ones that come from protein are burned instantly.  By comparison, carbs and fats have a thermic effect of ~10%.

Calories Are Still King

Are you sold yet?  High protein consumption is kinda awesome.  But when it comes to actually losing weight, calories are still king.  Caloric intake is the defining factor of any weight loss program, it’s basic nutrition.  Your body uses energy to walk, talk, think, and, as we pointed out above, digest food.  When there’s extra energy available, your body converts the surplus into fat stores to be used down the road instead of wasting it.  When your body goes through periods of energy shortage, it draws from these reserves to maintain its standard level of operation (12, though the resting metabolisms here seem high to me).  In order to lose these energy reserves, your body must encounter an energy shortage which is how we get to caloric restriction.  From here, many people make the jump to thinking they should just cut out all calories to maximize fat loss.  A higher caloric deficit leads to quicker weight loss, right?  Unfortunately, no.

A term that gets thrown around in the weight loss circles is “starvation mode.”  “Starvation mode” is a myth that your body stops burning calories when it notices a deficit making weight loss impossible.  Like most myths though, it has some roots in actual science.  I think two of these roots in particular are worth talking about.

The first idea that “starvation mode” draws from is the dynamic nature of the energy balance equation.  If you read the link above, you’ll know that calories stored = calories consumed – calories burned.  What you may have missed though is that when your calories burned is a dynamic variable, not a fixed one (13).  This means that it changes based on present conditions, it will not be the same across the board.  The clearest way to illustrate this is to compare the basal metabolic rates (BMRs) of two different body types.  If you take a male and a female with the same weight, height, and age, the male will have a higher BMR.  If you take two males with the same height and age but different weights, the heavier one will have a higher BMR.  Now what happens when you start your diet at 250lbs and lose 50lbs over a year?  You’re (likely) still your respective sex, your height hasn’t changed much, but now you’re one year older and 50lbs lighter.  Let’s go back to that BMR equation and what happened?  Your calories burned variable has decreased by about 300cal/day.  So, yes, as you lose weight your body burns calories more slowly.  Not because you are “starving” but because it takes less energy to power a smaller body.

Root number two that should be addressed is that there is a maximum to how much fat you can burn in a day (1415).  Think of it this way.  Your fat cells need to package and ship the calories they’ve got off to the blood stream so they can circulate and be used.  Only problem is, they can only work so fast.  Like USPS during the holidays, they can’t keep up with demand past a certain point.  This point is roughly 30cal/day for every pound of fat in your body.  In a 200lb male with 20% body fat (40lbs), he could theoretically diet at a maximum deficit of 1200 calories.  A bit extreme, but it is a maximum.

So now we’ve got a couple of the biological factors that limit how effectively a body can diet.  There is one last piece that plays into my 10-20% recommendation, the mental health equation.  Now roughly expressed,

       mental health = [hours of quality sleep / 8] + [(calories eaten – calories burned) x10 / calories burned] + [hours spent looking at cat pictures/1]

The source on that equation is me. But, for real, mental health is a massive component of any lifestyle.  If you aren’t happy with how you’re living, it won’t be sustainable.  Sure you could force it and make things work, but is it really worth it in the end if your chasing a goal that may never come instead of living in the moment?  Going back to our 200lb, 20%BF male, a 1200 calorie deficit is no fun at all.  Energy levels are drained across the board, hunger is distracting, attention span and reflexes decrease.  Something that major significantly decreases quality of life across the board.  Sure he could probably drop 20lbs in a month, but he likely won’t have developed good nutritional habits and he would have sacrificed that month of his life instead of living it.  Like I said back in the protein section, the goal here is long term change to prevent failure and regaining the lost weight at a later point.

The Wrap Up

To sum it all up, the version of flex dieting I recommend all comes down to those two rules at the beginning:

  1. Eat at a 10-20% calorie deficit
  2. Eat one gram protein per pound body weight

These two guidelines will get you 80-90% of the way when it comes to dieting.  There are other elements that can be introduced to increase the effectiveness of the dieting process, but it comes down to a cost/benefit analysis.  Each new rule introduces another level of complexity and stress which will reduce long term adherence.  If your interested in how to double down on the weight loss process, I would recommend looking into ketogenisis (the keto diet) or meal timing (whether intermittent fasting, multiple small meals, or some other variation).  I would stay away from anything people try to sell you when it comes to dieting.  Some supplements are worth adding, but only if you are invested enough in the process to do the research on your own.

And that’s it.  We live in a world where everyone has a big secret that’ll help you shed pounds for only $49.95, but, when it comes down to it, if your diet relies on tips, tricks, and secrets, you’ve already failed.  Nutrition is a simple concept that has been complicated by the fitness industry.  And that’s why I took the time to make this post.  At Catalyst, we believe that the user manual for you body should be presented in an easy to read form, free of charge.  Everyday we talk to friends, family members, and clients who don’t understand why they can’t lose weight.  They hop from diet to diet exhausting themselves and eventually reach a place where they give up.  So this is for them and everyone else who feels lost when it comes to their body, we hope you enjoy it as much as we do.