Carbohydrates are the most misunderstood nutrients when it
comes to fat loss. Far too many people, my past self included, have completely
removed carbs from their diet in an effort to speed up fat loss.
However, for most people, the best fat loss results actually come
from consuming carbs, not completely cutting them out. A big
reason for this is the specific fat burning hormones that only
respond when carbs are strategically part of your diet.
This is a critical point, because hormones flat out decide whether
or not you are a fat burning machine or just on the road to ending
up a skinnier version of yourself with very little change in body fat.
The fact is, anyone can lose weight by simply eating very low
calories. But just because you are losing weight doesn’t mean
you are losing much body fat. Just “losing weight” hopefully
is not your goal.
You want fat loss! And in order to target body fat, you absolutely
must have your hormones under control.
Here are the 4 biggest hormonal players in the fat burning game
and how the practice of avoiding carbs puts the brakes on your
1. Leptin: This hormone is known as the “fat burning hormone”.
When leptin is elevated your body is sending the signal to start
burning away at body fat stores.
Leptin is released from fat cells. The more body fat you have
the more leptin your body will release. As you begin to diet for
fat loss, the reduction in calories and the loss of body fat naturally
leads to less circulating leptin. When leptin levels are lowered,
fat burning slows down.
Carbohydrate containing meals happen to be the best way to
keep leptin elevated so that you keep burning fat. On the flip
side, a low carb diet keeps leptin depressed shutting down your
2. Cortisol: You’ve probably heard cortisol described as
the stress hormone responsible for accumulation of belly fat.
If you haven’t heard this, cortisol is the stress hormone
responsible for the accumulation of belly fat. 😉
Anytime your body is placed under stress, (physical, emotional,
or mental) the response is to produce cortisol. When cortisol
gets out of control, your abdominal fat begins to get packed on.
Carbohydrates are essential for keeping cortisol balanced.
Carbs provide an easy energy source for the body, in the form
of glucose. When glucose levels are optimized there is no
stress response needed to produce energy.
However, when carb intake is kept very low, there are lower
levels of readily available glucose to be utilized. In this case,
cortisol is released in order to free stored energy and provide the
glucose needed to keep you going.
If cortisol continues to be released due to low energy levels,
as is the case with chronically low carb diets, the end result
is belly fat accumulation.
3. Thyroid Hormone: This hormone is produced by the thyroid
gland and is largely responsible for your metabolic rate. In other
words, healthy levels of thyroid hormone keep your metabolism
buzzing, whereas depressed levels of thyroid hormone bring fat
burning to a halt.
I’m sure you can guess what is coming next. Low carb diets
lead to reduced levels of thyroid hormone putting the brakes on
your fat burning efforts. By limiting carbs too heavily, you can
actually end up shutting down your metabolism.
4. Insulin: When you eat carbohydrates they are broken down into
glucose and your blood sugar becomes elevated. This in turn, signals
your pancreas to release insulin.
Insulin’s job is to deliver the sugar from the blood into muscle
cells making insulin a very anabolic hormone. In a perfect, fat
burning world, the story ends there.
However, we don’t always live in a perfect fat burning world.
Eventually, your muscle cells get “topped up” and can no longer
take in any more sugar. Once your muscle cells are no longer
accepting sugar, insulin deposits the remaining energy into body fat.
In this way, insulin can be responsible for making you fatter.
Hence, the low carb diet was born with the idea that if you
completely eliminate carbs from the picture, blood sugar will
remain low, insulin will be under control and you will be able
to avoid fat accumulation.
Now, this works to a degree and short bursts with very little
carbs can work wonders for fat loss, but this is not the most
effective way to keep your fat loss humming through the entire
duration of your diet.
Enter “Insulin Sensitivity”. This term, insulin sensitivity, refers
to your muscle cells willingness to accept insulin (carrying blood
sugar) so that it can be properly distributed. When you are highly
insulin sensitive, sugars get deposited in the right place (muscle
cells) and avoid being stored away as body fat.
However, because it is carbohydrates that create the most
profound effects on insulin, by going too long with very low
carbs in your diet and not experiencing bursts of insulin your
muscle cells essentially will start rejecting insulin, leading to
insulin resistance. When insulin resistance occurs you go into
fat storing mode.
All four of the above hormones need to be balanced for optimal
fat burning efforts. Get any one of them out of whack and you
can say goodbye to fat burning.
And when you cut carbs too low for too long, you run the risk
of hormonal imbalance.
So stop fearing carbs, instead use them responsibly and strategically
to Turbo-Charge your fat loss.
Thanks James Gaida for this awesome, eye opening, article!
Keeping an eye on you in health and fitness,
Mark Lani CPT , CSN
Certified Personal Trainer
Certified Sports Nutritionist