When You Lose Weight, Where Does the
Lost Fat Go?
January 09, 2015
Story at-a-glance
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When you lose weight, you exhale 84 percent of the lost fat
in the form of carbon dioxide. The remaining 16 percent is
excreted as water via bodily fluids
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By substituting one hour of sedentary lounging with one hour
of moderate exercise—to increase your respiratory rate—your
metabolic rate is increased sevenfold
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If you are insulin or leptin resistant, as long as you keep
eating fructose and grains, you're programming your body to
create and store fat
By Dr. Mercola
The vast majority of doctors, dietitians, and personal
trainers believe that when you burn fat during exercise, that
fat is being used up as fuel for energy or heat. Some believe
it’s excreted through urine or feces, while others think the fat
is turned into muscle.
All of these ideas are to some degree incorrect, according to
Ruben Meerman, a physicist, and Andrew Brown, a biochemist
specializing in lipids, who say there’s "surprising ignorance
and confusion about the metabolic process of weight loss."
When You Lose Weight, Where Does the Fat Go?
Their calculations, showing where the fat really goes when
you lose weight, was recently published in the journal BMJ.1,2
As explained by Medical News Today:3
“Excess dietary carbohydrates and protein are
converted to a type of fat called triglyceride. When people
attempt to lose weight, they are attempting to metabolize
these triglycerides while keeping their fat-free mass
intact...
Triglycerides are comprised of three types of atoms:
carbon, hydrogen and oxygen. Triglyceride molecules can be
broken down only by unlocking these atoms, through a process
known as oxidation.
The researchers chose to follow the path of these
atoms when leaving the body. They found that when 10 kg of
fat were oxidized, 8.4 kg were converted and excreted as
carbon dioxide (CO2) via the lungs, and 1.6 kg
became water (H20).
In order for 10 kg of human fat to be oxidized, the
researchers calculated that 29 kg of oxygen must be inhaled.
Oxidation then produces a total of 28 kg of CO2
and 11 kg of H20.”
The researchers note that this is not new to science—rather
the process has simply been misunderstood. The equation does
involve release of energy; it’s just that the process isn’t as
direct as one might think. According to the law of conservation
of mass, it’s actually quite difficult to convert matter into
energy.
As noted by The Atlantic:4
“If you were able to convert your fat stores [directly] into
energy, you would explode in a glorious, catastrophic
spectacle...” According to their calculations, you
basically exhale 84 percent of your lost fat. The
remaining 16 percent is metabolized into water, which is
excreted through sweat and urine.
The authors estimate that by substituting one hour of
sedentary lounging with one hour of moderate exercise—to
increase your respiratory rate—your metabolic rate is increased
sevenfold. However, they note that you can easily hamper any
potential weight loss by eating too much food—and I would
stress, by eating the wrong kinds of foods.
Your Food Choices Make a Huge Difference
It’s important to recognize that most people who struggle
with excess weight have some degree of insulin and leptin
resistance. Leptin is a hormone that helps you regulate your
appetite. When your leptin levels rise, it signals your body
that you're full, so you'll stop eating.
As you become resistant to the effects of leptin, you end up
overeating, as your body gradually loses its ability to “hear”
the signals leptin sends out.
Dr. Richard Johnson's research clearly shows that refined
sugar (in particular processed fructose) is exceptionally
effective at causing leptin resistance. Fructose also
effectively blocks the burning of fat.
Basically, if you are insulin or leptin resistant, as long as
you keep eating fructose and grains, you're programming
your body to create and store fat. This is one of the
key reasons why, if you are overweight, you’d be wise to
restrict your fructose consumption to about 15 to 25 grams of
fructose per day from all sources.
This means switching out most processed foods for whole,
unprocessed foods, and avoiding any and all sweetened beverages.
Clean pure water is really the only type of fluid your body
needs. For further dietary guidance, please see my
comprehensive nutrition plan.
If you’re insulin/leptin resistant and/or are overweight, you
can also greatly boost your body's fat-burning potential by
incorporating
intermittent fasting, as it helps reset your body to use fat
instead of sugar as its primary fuel. It is by far the most
effective way I know of to shed unwanted fat and eliminate your
sugar cravings.
Exercising in a fasted state (such as first thing in the
morning) will bring it up yet another notch. A simple way to get
started with intermittent fasting is to simply omit breakfast,
making lunch the first meal of your day.
Maintain this daily eating schedule until your insulin/leptin
resistance improves (weight, blood pressure, cholesterol ratios,
or diabetes normalizes). After that, just do it as often as you
need to maintain your healthy state.
White versus Brown Fat
While we’re on the topic of fat, it’s worth noting that there
are different kinds of fat cells in your body, and from a
metabolic standpoint, they respond differently. They even appear
to have different biological functions. None of this was
discussed in the featured research, but it likely also plays a
role in the big scheme of things. For a number of years,
scientists have been studying so-called "brown
fat"—a type of fat that generates heat that burns energy
instead of storing it. So-called “white fat” is the kind that is
primarily stored, and because it’s also difficult to burn off,
it tends to cause obesity. Research has shown that certain
groups of people tend to have more brown fat than others, and
there appears to be direct correlations between the activation
of brown fat and metabolic measures of good health. For example:
- Slender people have more brown fat than obese people do
- Younger people have more brown fat than elderly people
- People with normal blood sugar levels have more brown
fat than those with high blood sugar
How to Transform White Fat into Healthier Brown Fat
Newborns have a supply of brown fat to keep warm, but most of
these stores are lost by the time adulthood is reached. However,
although you have far less of it as an adult, scientists have
found that you can activate the brown fat still present in your
body by exposing yourself to cold temperatures. This has the
effect of causing your body to burn more calories to keep warm,
and there’s evidence suggesting
ice therapy can be helpful for boosting weight loss. Animal
research has also shown that animals convert white fat into
brown fat simply by exercising.
The study,5
published in the journal Disease Models and Mechanism,
found that during exercise the animals' muscles released an
enzyme called irisin, which triggered the conversion of white
fat cells to brown. Preliminary studies presented at the 2013
annual meeting of the American Diabetes Association revealed
that this holds true in humans as well. Among men, the benefits
were found after 12 weeks of training on an exercise bike. One
of the researchers, a postdoctoral fellow at Joslin Diabetes
Center, said:6
"Our results showed that exercise doesn't just have
beneficial effects on muscle, it also affects fat… It's
clear that when fat gets trained, it becomes browner and
more metabolically active. We think there are factors being
released into the bloodstream from the healthier fat that
are working on other tissues."
As you can see, the human metabolism is extremely complex. On
the one hand, exercise helps convert unhealthy white fat into
healthier, heat-producing and more metabolically active brown
fat. Exercise also increases the oxidation of fat, which then
leaves your body via your lungs, in the form of carbon dioxide,
and your bodily fluids, in the form of water. What’s not
so complex however, is how to optimize your metabolism—even
if you don’t understand the exact mechanisms involved. Following
simple basics described below will catalyze your body’s ability
to achieve your ideal weight and leanness.
Your Weight Reflects Your Lifestyle Choices
Simply eating fewer calories and exercising more usually
doesn’t work very well, and the reason for that is because not
all
calories are the same. As mentioned, processed fructose in
particular causes leptin resistance far more effectively than
other sugars, with refined sugar coming in close second. Glucose
is not nearly as harmful in comparison. Fructose also blocks the
burning of fat. So, instead of focusing on calories, you need to
address the quality of the foods you eat, and avoid
chemical exposures. Endocrine-disrupting chemicals such as
BPA and phthalates, for example, can cause or exacerbate
weight gain. Following is a short list of proactive,
easy-to-remember guidelines that can go a long way toward
improving your health, nutrition, and body weight.
- Exercise regularly, and stay active all day long:
Engage in
high-intensity Peak Fitness exercise to burn fat and
increase muscle mass (a natural fat burner). Also, strive to
sit less (much less—ideally no more than three hours a day)
and walk 7,000 to 10,000 steps a day in addition to your
regular exercise program.
- Consider intermittent fasting: If
you’re insulin/leptin resistant and/or are overweight, boost
your body's fat-burning potential by incorporating
intermittent fasting. This is one of the most powerful
approaches to reverse insulin resistance. It is only
necessary to do until your insulin resistance resolves.
- Buy real food, preferably whole organic and
locally grown, and cook from scratch. Ditching
processed foods will automatically reduce your sugar
consumption, which is the root cause of insulin resistance
and weight gain. If you buy organic produce, you’ll also cut
your exposure to pesticides and genetically engineered
ingredients, and in ditching processed foods, you’ll
automatically avoid artificial sweeteners and
harmful processed fats like trans fats and vegetable
oils (such as peanut, corn, and soy oil), the latter of
which actually degrades into oxidation products when heated
that may be more harmful than trans fat.
That said, most people do need upwards of 50-85
percent healthy fats in their diet for optimal health.
Sources of healthy fats to add to your diet include
avocados, butter made from raw grass-fed organic milk, raw
organic dairy, coconuts and coconut oil, unheated organic
nut oils, raw nuts and seeds, organic pastured egg yolks,
and grass-fed meats. For more detailed dietary advice,
please see my free
Optimized Nutrition Plan.
- Opt for organic grass-fed meats to
avoid genetically engineered ingredients, pesticides,
hormones, antibiotics, and other growth promoting drugs.
- Opt for glass packaging and storage containers
to avoid endocrine disrupting chemicals.
© Copyright 1997-2015 Dr. Joseph Mercola. All Rights Reserved.
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