What's Going On with Stubborn Fat? Part 2

If you're just dipping your toes into understanding the physiology of fat loss, last week's Part 1 is a good place to start.  I think the prevailing mindset for many is that fat loss or gain is a one-way street.  However there are many influencing factors on fat loss and the process from the outside can appear simple "just eat less" the internal mechanisms are anything but.

It's pretty rare that someone attempts fat loss once and is completely successful to their satisfaction.  I'd hazard a guess to say it almost never happens and it is not something I've ever witnessed.  Part of this is for reasons discussed last week in that there will be stubborn fat that takes much more adherence, consistency and work to burn off. Misconceptions and perhaps unrealistic expectations are the reasons so many of us give up when fat loss becomes difficult.

Once again, understanding this even on a basic level can help you work through plateaus and stubborn fat.

To recap last week's bullet points:

  • Fat need to be mobilized first before it can be transported and burned off
  • HSL is the primary hormone in fat mobilization.  Certain hormones enhance it like the catecholamines while insulin directly opposes it
  • Mobilization is not enough, fat also needs to be transported away from the fat cell
  • Blood flow has a direct impact on how well fat is mobilized away from the cell
  • The hormones that help primarily with mobilization ALSO increase blood flow which helps with transport
  • Visceral fat has the highest blood flow and will be mobilized first but may not result in much change in appearance or measurements despite being burned off
  • Men and women store bodyfat in different patterns: men have more visceral fat and will usually see faster initial weight loss simply because of where the fat is stored and the blood flow to that area

Fat Burning

We finally get to the good stuff, actually burning the fat!  Once fat is mobilized outside of the fat cell, transported away from the cell in the blood and into general circulation the fat can enter a few key areas to be burned or "oxidized". Your muscles are the primary tissue that will oxidize fat although the heart and liver have the ability as well.  Inside the muscle cell, the fatty acid enters the mitochondria which, if you remember high school biology (or other posts of mine), is considered the powerhouse of the cell and where oxygen is used to ultimately gain ATP energy from fat. Other byproducts of this process include carbon dioxide and water.

As I mentioned last week, this process of fat oxidation is constantly occurring.  Fat is being stored, mobilized, transported and oxidized all the time but if energy intake is less than energy expenditure you will oxidize more fat than you burn!

Stored Energy in the Muscles

Your muscles hae the ability to store both glycogen (carbohydrates) and intra-muscular triglycerides (fat).  Once these fuels are stored in the muscle they can never re-enter the bloodstream, the simply wait in store to be used by the muscle for energy.  Having high levels of both (meaning most likely being in a calorie surplus or at least maintenance) will decrease the use of stored body fat for fuel.

Performance Tip: One interesting piece of physiology above is that eating and storing a lot of fat and carbohydrates in the muscle probably means low body fat burned.  So, in a calorie deficit you obviously will lower carbs or fat, or a combination of the two.  Now here's where you can optimize performance - research shows that a muscle is more anabolic and less prone to to protein breakdown when it has higher glycogen levels (meaning you are eating more carbs).  If you are optimizing performance and have a high workload in the gym or on the field and want/need to lean out, I'd opt away from a really low-carb approach.  Keeping fat lower in this case and creating the bulk of your calorie deficit from dietary fat allows for greater muscular glycogen content which will not only improve performance but might give you an anabolic (muscle building) edge.

Easy and Stubborn Fat

We already discussed visceral fat being an area of high fat storage but also high fat burning.  Proximity to organs and high bood flow make this type of fat relatively easy to lose.

Subcutaneous fat (fat under the skin) obviously has less blood flow than deep visceral fat which makes it more difficult to lose or at least secondary to visceral fat.  At the beginning of a diet you probably lean out first in the area around your organs which may or may not affect your appearance and measurements at first, although you might feel better overall.  Next will come fat burning from subcutaneous fat in the areas most easily burned.

Upper body suncutaneous fat (think chest, arms, shoulders and abdomen) is more easily mobilized, transported and burned than lower body fat.  The two upper body areas most difficult to lose however are upper and lower abdominal fat.  This is the stomach area and lower abdominal (bellybutton down) is the most difficult. Practically speaking many people will experience this with the arms, chest and shoulder leaning out first, then the upper stomach then FINALLY the lower stomach.

Lower body fat has less blood flow and in women is far more resistant to fat loss than the upper body.  We touched briefly on catecholamines (think adrenalin) and how they enhance fat loss.  Interestingly, catecholamine receptors can be divided into alpha and beta with "beta" receptors stimulating fat loss much more than "alpha".  Whereas the upper body has more beta receptors which enhance fat loss, the lower body has much more alpha receptors which down regulate fat loss.

Men vs Women

Not in combative sense of course!  However there are some major differences in how men and women store and lose fat and that can be largely derived from hormonal differences. I have to give credit to Menno Henselmans for writing  this piece on Biosignature and he outlined some key and enlightening differences in hormonal effect's on fat loss.


In men, testosterone has a decentrilization effect, meaning it inhibits fat storage around the midsection.  Cortisol, especially in the presence of insulin promotes fat storage primarily in the torso - testosterone works to oppose cortisol and insulin's fat storing affects.  You'll see this hormonal losing battle in ageing men with lower testosterone or individuals stressed to the max, not sleeping well and eating poorly; they'll have chronically high cortisol and insulin which will overpower testosterone's ability to keep midsection fat at bay.

In women, testosterone actually enhances mid-section fat storage which is why in cases like post-menopausal, PCOS or morbid obesity where testosterone is high, more fat is stored on the midsection.


Consider estrogen having the same muscle building and fat burning effects in women as testosterone does in men.  In women, estrogen decentralizes fat storage, meaning it opposes fat storage around the stomach.  Since we dicussed women having much high alpha catecholamine receptors in the lower body which inhibit fat loss and lower blood flow, the lower body will see more fat storage and more resistance to fat loss than the upper body.  Estrogen directly opposes cortisol and insulin's fat storage effects just like testosterone does in men.

You can see this example in a practical sense all the time.  Men have a pretty even fat storage and when testosterone is low (like in older age) or cortisol and insulin are high, they'll get a belly while most of the rest of the body stays lean.  Women with high estrogen have more curvy hips with flat stomachs and lean upper body.  When estrogen is low or cortisol and insulin are high, fat storage shifts to leaner limbs and a more fat on the torso.

In simple terms, your healthy hormone levels are keeping your midsection lean! They won't directly affect HOW much fat you lose but they will impact where it is stored.

The Practical Approach

While you can see above how your hormones affect your fat storage pattern, the ket determinant of fat loss is your energy balance i.e consuming fewer calories than you expend.  I cannot stress the importance of tackling ALL the secondary factors that will have an impact on your cortisol, insulin and catecholamines as having high levels of stress and chronically high insulin will make fat loss harder and impact where you store it and where you burn it.

While people cite the "twinkie diet" as proof that you can lose weight eating like garbage if you eat in a calorie deficit, don't overlook the practical implications.  The professor who ran the twinkie diet for 10 weeks lost 27lbs.  He ate mostly snack foods and had a daily protein shake.  This helps drive home the fact that calorie balance affects WEIGHT but does not entail whether the weight is fat or muscle (or even water).  In an interview with Professor Haubs, he claimed he felt awful while on the diet with mood swings, lethargy and poor concentration.  He also noted he got weaker and probably lost a good deal of muscle mass.

So while calorie balance IS the number one driver of weight loss or gain, prioritizing your health will have a huge impact on retaining muscle, losing mostly fat, balancing blood sugar, keeping cortisol in check and allowing you to feel clear headed, energized and able to recover from work, the gym and life stress.

Energy In

You essentially have one means of energy in; the food you eat.  It is a pretty simple concept and any easier metric to control than energy out which is why diet has the largest impact on body weight and composition.  You control one entire half of the equation with one simple means - how many calories you eat.  

In order to maximize this you want optimal protein which will keep muscle protein breakdown at bay, strength train which helps with insulin sensitivity, stress relief and has a greater net muscle-retention effect (as long as protein is high enough).  You also want adequate fiber to help with healthy bowel movements, control blood sugar and keep you full and choosing mostly whole foods which take more energy to digest, keep you satiated longer and usually have more micronutrients.All of these things are giving you an edge and promoting more muscle and less fat.  Total WEIGHT lost might be the same without them but it'll be more weight from muscle which is a major red flag.

Energy Out.

Here's where I'll leave you this week before wrapping it up next week.  Energy out is more complicated and involved than energy in.  Your energy out comes from:

  • Resting Metabolic Rate: This is the energy cost of simply keeping you awake and alive and is about 75% of total calories burned daily. This is primarily made up of organ activity which accounts for about half of all calories expended daily while muscular activity is around 20%
  • Thermic Effect of Food: This is the amount of energy used to digest and assimilate food.  Each macronutrient differs in how much energy it takes to digest with protein being the highest around 15-25%, carbohydrates being 6% and fat being 3%.  This also helps reinforce why greater protein intake (and yes even carbs) can help with fat loss as they take more energy to digest
  • Thermic Effect of Activity: Surprisingly small for most of us.  Athletes with double-digit hours training will expend much more but for the average person training 3-5 days per week for an hour you can expect perhaps a 5-10% of total energy expenditure coming from exercise
  • N.E.A.T: This is Non-Exercise Activity Thermogenesis and consists of all activity not exercise related such as gardening, walking up stairs, strolling around the grocery store as well as unconscious movement like fidgeting and tapping. N.E.A.T is my favorite to discuss as it largely explains the energy expended between individuals of similar size whereas two 150lb women may have huge differences in energy output with the difference coming down to their N.E.A.T, 


This is also a predictor of fat loss and helps dispel the myth of a slow metabolism.  Individuals who are overweight in fact have FASTER metabolic rate as thyroid ouput increases with body weight in an attempt to keep you from gaining more.  In essence, the larger you are the "faster" your metabolism. 

So we can move past that ideaology to addressing N.E.A.T as an area individuals who eat relatively well but have trouble leaning out can work on.  Simply moving more and being more active will drive up calorie expenditure to a great degree. Some of this is genetically driven and people with high genetic N.E.A.T tap, fidget and move around a lot appearing  restless.  Some individuals will simply increase N.E.A.T subconsciously when they eat more which explains why they gain weight more slowly.  You'll also decrease N.E.A.T subconsciously when dieting so it is important to stay active in a general sense when leaning out.

Keep in mind that when dieting and training hard your body's response to conserve energy will be to move less at other times.  You might find when you watch TV you get up or fidget less on the couch, you might starting taking the elevator instead of the stairs, you might even start decreasing training intensity. If you can train intensely and get at least 8,000-10,000 steps daily you'll most likely keep N.E.A.T high enough to help give you a fat loss edge.

Remember that training should never suffer when leaning out as your strength training will directly impact your muscle retention and building, insulin sensitivity, body composition and appearance and to a small degree, your calorie expenditure.  This is why I advocate picking training times that YOU feel the best, having proper pre-workout protein and carbohydrates and proper post-workout protein.  Adequate hydration, taking 3-5g creatine per day and perhaps keeping carbs preferentially higher over fat can positively impact your results.  If you have a large amount of fat to lose you probably don't need to try t eat high-carb and low-fat as your body has eneough energy stores.  Keep in mind a larger individual leaning out ALSO has an easier time mobilizing body fat AND has a higher metabolic rate so there is no reason calories need to be so low they drastically impact carbohydrate consumption anyway.

The above is a major mistake, in my opinion, of coaches trying to maximize fat loss and giving larger individuals very low calories.  These people are actually in need of more calories overall, mobilize fat the easiest and also struggle with adherence generally so staying away from drastic diets will only optimize their results, create greater adherence and build long-term healthy habits.  Much smaller and leaner individuals are actually the ones who need less food, more complex dieting strategies and have a harder time mobilizing fat. 

Finally, next week we will touch on what to expect in terms of calorie deficits and fat loss, how much weight to expect to lose and what strategies will keep you leaning out long-term.