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Fat How it gets made and broken down

How does fat get made?

We eat to (a) have building materials for our cells, and (b) to get energy for chemical reactions in our cells.

Excess protein or carbohydrates get broken down, and rebuilt as fat molecules, usually triglycerides.

What happens to fat when it is broken down?

Eventually, broken down fat turns into CO2 and H2O. The H2O stays in your body as regular water, and excess water is removed by sweating and urination. The CO2 is removed as you exhale.

When you lose weight, where does it go? Turns out, most of it is exhaled.

Myth: Fat gets burned, and turned into “energy” or heat.

Reality: Fat is made of atoms. Those atoms get broken apart and rearranged into other molecules.

To lose weight, we must break triglycerides into smaller molecules. We need oxygen to do this. Part of this process is oxidation.

Doesn’t happen all in one step.

Some fats get converted to Aceryl-CoA and glycolysis intermediates, but even these will eventually break down int into CO2 and H2O.

When a triglyceride is oxidized the process consumes many molecules of oxygen while producing carbon dioxide (CO2) and water (H2O) as waste products.

So, for example, to burn 10 kilograms (22 lbs.) of fat, a person needs to inhale 29 kg (64 lbs.) of oxygen….
burning that fat will produce 28 kg (62 lbs.) of carbon dioxide and 11 kg (24 lbs.) of water.

“None of this biochemistry is new, but for unknown reasons it seems nobody has thought of performing these calculations before,” study authors Ruben Meerman and Andrew Brown of the University of New South Wales in Australia, said…. during weight loss, 84 percent of the fat that is lost turns into CO2 and leaves the body through the lungs, whereas the remaining 16 percent becomes water, according to the study.

“These results show that the lungs are the primary excretory organ for weight loss. The water formed may be excreted in the urine, feces, sweat, breath, tears or other bodily fluids, and is readily replenished,” the researchers said.

The calculations also show the frightening power of, for example, a small muffin over an hour of exercise: At rest, a person who weighs 154 pounds (70 kg) exhales just 8.9 mg of carbon with each breath. Even after an entire day, if this person only sits, sleeps, and does light activities, he or she exhales about 200 grams of carbon, the researchers calculated.  A 100 g muffin can cover 20 percent of what was lost.

On the other hand, replacing one hour of rest with exercise such as jogging, removes an additional 40 g of carbon from the body, the researchers said. Even if one traces the fates of all the atoms in the body, the secret to weight loss remains the same: In order to lose weight, one needs to either eat less carbon or exercise more to remove extra carbon from the body.

– Exhaled Pounds: How Fat Leaves the Body, Bahar Gholipour, Live Science, 12/14

Reference: When somebody loses weight, where does the fat go?
BMJ 2014; 349 doi: https://doi.org/10.1136/bmj.g7257 (Published 16 December 2014)

Abstract:  When somebody loses weight, where does the fat go?

Considering the soaring overweight and obesity rates and strong interest in this topic, there is surprising ignorance and confusion about the metabolic process of weight loss among the general public and health professionals alike. We encountered widespread misconceptions about how humans lose weight among general practitioners, dietitians, and personal trainers (fig 1⇓). Most people believed that fat is converted to energy or heat, which violates the law of conservation of mass. We suspect this misconception is caused by the “energy in/energy out” mantra and the focus on energy production in university biochemistry courses. Other misconceptions were that the metabolites of fat are excreted in the faeces or converted to muscle. We present a novel calculation to show how we “lose weight.”

Learning standards

Massachusetts Curriculum Frameworks: Biology

8.MS-PS1-1. Develop a model to describe that (a) atoms combine in a multitude of ways to produce pure substances which make up all of the living and nonliving things that we encounter, (b) atoms form molecules and compounds that range in size from two to thousands of atoms, and (c) mixtures are composed of different proportions of pure

HS-LS1-6. Construct an explanation based on evidence that organic molecules are primarily composed of six elements, where carbon, hydrogen, and oxygen atoms may combine with nitrogen, sulfur, and phosphorus to form monomers that can further combine to form large carbon-based macromolecules.
Clarification Statements:
• Monomers include amino acids, mono- and disaccharides, nucleotides, and fatty acids.
• Organic macromolecules include proteins, carbohydrates (polysaccharides), nucleic acids, and lipids.

Disciplinary Core Idea Progression Matrix: PS1.A Structure of matter

That matter is composed of atoms and molecules can be used to explain the properties of substances, diversity of materials, how mixtures will interact, states of matter, phase changes, and conservation of matter.


Evolutionary Origin of the Turtle Shell


This intro is lightly adapted from thelogicofscience.com

Many people mistakenly believe that there are two fundamentally different types of evolution: microevolution and macroevolution. They argue that microevolution does actually occur, but only produces small changes within a species or “kind” of animal. For example, they’re okay with the concept that all finches evolved from a common ancestor, all crows evolved from a common ancestor, all ducks evolved from a common ancestor, etc.

However, they draw the line roughly at the taxonomic level of family (e.g., ducks are in the Anatidae family), and they argue that evolution beyond that level (what they call macroevolution) is impossible and has never and can never happen. Thus, they dismiss the notion that finches, crows, and ducks all share a common ancestor.

However, this distinction is completely arbitrary and meaningless: the exact same evolutionary mechanisms that caused the evolution of finch species could (and indeed did) cause the evolution of all birds. In other words, macroevolution is simply the accumulation of microevolutionary steps, and one inherently leads to the other.

Here is a visual explanation. The image below shows a hypothetical pathway through which turtles could have evolved from their lizard-like ancestors.

Several of these images are renderings of actual fossils: B6 = Milleretta, A15 = Eunotosaurus, C22 = Odontochelys, B30 = Proganochelys, D37 = Chelydra [modern turtles]; these are just screen shots from Dr. Tyler Lyson’s excellent video.

This full progression is, of course, what creationists would consider to be macroevolution, and creationists are adamant that today’s turtle families were uniquely created and did not evolve from a lizard-like ancestor. However, because they accept microevolution, most creationists would have no problem with any particular pair of images, and they would accept that A1 could evolve into B1, B1 could evolve into C1, etc.

In other words, each pair of images shows “microevolution” (which creationists almost universally accept), but when we string all of those steps together, we get “macroevolution” (which they say is impossible).

You can probably see where I am going with this, but just to be sure, I will state it explicitly. If you are going to say that macroevolution is impossible and turtles could not have evolved from lizard-like ancestors, then which step do you think is impossible?

Please show me which step could not have occurred, and justify that claim. Additionally, please explain the obvious transitional fossils. Remember, B6, A15, C22, B30, and D37 are actual fossils, and they perfectly match the expectations for what a transitional fossil should look like (details here). So, if turtles and their lizard like ancestors were uniquely created kinds, then at what point in this progression do lizard-like reptiles end and turtles begin?

Image from “Evolutionary Origin of the Turtle Shell” by Tyler Lyson









And here is the amazing video

Continued from “The Logic of Science”

Some people will likely be inclined to ignore my questions and harp instead on the fact that this pathway is hypothetical, but that argument completely misses the point in several ways. First, this pathway is only partially hypothetical because B6, A15, C22, B30, and D37 are actual fossils that we have found.

Additionally, of course the pathway is partially hypothetical. We will never find every single one of these steps, and we don’t need to: Evolution is very much like the visible light spectrum. Each color gradually fades into the next color without a clear breaking point. In other words, there is a point along the spectrum that is clearly red, and there is a point that is clearly blue, and there is a point that is clearly violet, but there is a spectrum of change in between those points – and it is not possible to pick an exact point where the blue ends and violet begins, just as you cannot pinpoint the exact step at which the reptile becomes a turtle as we know it.


Evolutionary Origin of the Turtle Shell
Tyler R. Lyson, Gabe S. Bever, Torsten M. Scheyer, Allison Y. Hsiang, Jacques A. Gauthier
Current Biology, Published Online: May 30, 2013
DOI: https://doi.org/10.1016/j.cub.2013.05.003



Healthy diets

Construct Daily Diet Plant based


Vegan Protein nuts vegetables

Healthy plant-based diets – “A diet based on fruits, vegetables, tubers, whole grains, and legumes; and it excludes or minimizes meat (including chicken and fish), dairy products, and eggs, as well as highly refined foods like bleached flour, refined sugar, and oil.”


Changes to the American diet over the last century and health effects thereof

Old American diet

* Near the start of the 20th century, Americans each ate about 120 lbs if meat per year. By 2007, we ate about 222 lbs.

* About 1913, Americans ate about 40 lbs of processed sugar per person. By 1999, it had increased to 147 lbs per person.

* About 1909, Americans ate about 294 lbs of dairy products per person. By 2006, that number was over double…605 lbs of dairy per person!!

* This information came from the companion book to Forks Over Knives.

Write about health effects due to these changes


The China Study

The China Study is a book by T. Colin Campbell (2005.)  The China Study examines the relationship between the consumption of animal products (including dairy) and chronic illnesses such as coronary heart disease, diabetes, breast cancer, prostate cancer, and bowel cancer. The authors conclude that people who eat a predominantly whole-food, plant-based diet—avoiding animal products as a main source of nutrition, including beef, pork, poultry, fish, eggs, cheese, and milk, and reducing their intake of processed foods and refined carbohydrates—will escape, reduce, or reverse the development of numerous diseases. … The book is loosely based on the China–Cornell–Oxford Project, a 20-year study—described by The New York Times as “the Grand Prix of epidemiology”—conducted by the Chinese Academy of Preventive Medicine, Cornell University, and the University of Oxford. (Wikipedia)

Dean Ornish Diet – tba

Ornish is known for his lifestyle-driven approach to the control of coronary artery disease (CAD) and other chronic diseases. He promotes lifestyle changes including a whole foods, plant-based diet, smoking cessation, moderate exercise, stress management techniques including yoga and meditation, and psychosocial support. Ornish does not follow a strict vegetarian diet and recommends fish oil supplements; the program additionally allows for the occasional consumption of other animal products. (Wikipedia)

The Engine 2 Diet/Rip Esselstyn

– Details tba

Jeff Novick diet

The Five Pillars of Healthy Eating: “A Common Sense Approach To Nutrition”

1) Plant-Centered – Center your plate and your diet around minimally processed plant foods (fruits, vegetables, starchy vegetables, roots/tubers, intact whole grains, and legumes (beans, peas & lentils).

2) Minimally Processed – Enjoy foods as close to “as grown in nature” with minimal processing that does not detract from the nutritional value &/or add in any harmful components.

3) Calorie Dilute – Follow the principles of calorie density choosing foods that are calorie adequate, satiating and nutrient sufficient.

4) Low S-O-S – Avoid/minimize the use of added Salts/sodium, Oils/Fats and Sugars/sweeteners

5) Variety – Consume a variety of foods in each of the recommended food groups.

from http://www.jeffnovick.com/RD/Q_%26_As/Entries/2013/8/21_The_Healthy_Eating_Placemat_A_Visual_Guide_To_Healthy_Eating.html

Also see


This excerpt from an interview summarizes Jeff Novick’s view:

Consume a variety of foods in each of the recommended food groups. Now, if there were ten of us in the room, we could each implement these pillars slightly differently and still each have a healthy diet and great health results. That’s because when we look at the research evidence, there’s no one specific diet that is “best.” Instead, there are common denominators across healthy diets that combine to make up a healthy dietary pattern, and these are reflected in my five guidelines/principles of healthy eating.

What foods do you recommend that people incorporate into their diets? The healthiest foods are minimally processed fruits, vegetables, starchy vegetables, roots/tubers, intact whole grains, and legumes. These should make up most—if not all—of our daily calories. I recommend that people start right where they are and just keep adding in more of these foods each day.

It seems today that the topic of nutrition and health has become a war with sides drawn and no discussion. I am disappointed in the conversation I see happening on social media because a lot of it is very judgmental, confrontational, and elitist. The message out there seems to be that if the food you eat is not fresh, organic, local, shade-grown, GMO-free, and picked yourself or picked up at a local farmer’s market or purchased from some elite health food store, then all blended together in some expensive hi-tech blender, you are not doing well enough. And, if you buy any frozen or canned foods, you might as well be eating bacon and cheeseburgers.

We need to have compassion, not only for the animals and the environment, but also for our fellow humans, particularly in the way we treat each other, especially those who may not follow the exact same dietary pattern we do.

source: An interview with healthy eating expert Jeff Novick, posted on Jewishfoodherocom, Dec. 2015

Jeff Novick Healthy Eating Placemat

Jeff Novick’s Healthy Eating Placemat

Virginia Messina’s Vegan for Life

“Given what we know about the benefits of plant foods that are rich in healthful fats, it’s reasonable to expect that higher-fat, plant-based diets would be just as beneficial and perhaps have even more benefits,” says Virginia Messina, MPH, RD, vegan expert and coauthor of Vegan for Life. A Czech Republic study found benefits for people with diabetes who followed a high-fat (38%) almost-vegan diet.6 Messina also highlights that Esselstyn’s study didn’t include a control group or look at effects of weight loss and other potentially confounding variables, making it difficult to draw conclusions about the true effects of fat restriction. “We just don’t have the data to suggest that restricting dietary fat intake is necessary for good health and for treating disease. It’s much more likely that building a diet around healthful plant foods and choosing healthful fats is important,” Messina adds.

from http://www.todaysdietitian.com/newarchives/1016p20.shtml

Dietary Approaches to Stop Hypertension (DASH) diet

The popular Dietary Approaches to Stop Hypertension (DASH) diet was created to lower blood pressure, but new research says it can also reduce the risk of depression later in life. A study, to be presented at the American Academy of Neurology’s 70th Annual Meeting in April, shows that the popular diet — rich in vegetables, fruit, whole grains, fat-free or low-fat dairy products and very few foods that are high in saturated fats and sugar — does more than what has been shown in multiple studies: Lowering blood pressure, bad cholesterol (LDL) and body weight….

The odds of becoming depressed over time was 11 percent lower among the adults who followed the DASH diet more closely. The group that followed a Western diet — high in saturated fats and red meats, low in fruits and vegetables — were more likely to develop depression.

The Mediterranean diet recommends emulating how people in the Mediterranean region have traditionally eaten, with a focus on foods like olive oil, fish and vegetables. U.S. News and World Report called the diet a “well-balanced eating plan” when placing it at the top of its best diets for 2018 list in January.

The DASH diet has been ranked as the No. 1 overall diet by U.S. News and World Report for eight consecutive rankings. Originally started by the National Heart, Lung, and Blood Institute (NHLBI) as a diet to help reduce blood pressure, the DASH diet is made up of low-sodium and healthful foods. The NHLBI publishes free guides on the plan so you can see if it is right for you.

“The thing about the DASH diet is you’re eating specifically the foods you’ve always been told to eat, pretty much fruit, vegetables, whole grain, lean protein and low-fat dairy,” Angela Haupt, assistant managing editor of health at U.S. News and World Report, told ABC News in January. “And it eliminates foods high in fat and sugar-sweetened drinks and sweets.”

Dr. Jay Sheree Allen, ABC News

Popular diet doesn’t only reduce hypertension, but risk of depression as well, per study

What is the DASH diet? Heart-healthy diet may also reduce risk of depression

Do vegetarians need to engage in protein combining?

Protein combining is a dietary theory for protein nutrition that purports to optimize the biological value of protein intake. According to the theory, vegetarian and vegan diets provide insufficient content of essential amino acids, making protein combining necessary. The theory has been roundly discredited by major health organizations. Studies on essential amino acid contents in plant proteins has shown that vegetarian and vegans in fact do not need to complement plant proteins in each meal to reach the desired level of essential amino acids as long as their diets are varied. The terms complete and incomplete are misleading in relation to plant protein. Protein from a variety of plant foods, eaten during the course of a day, supplies enough of all essential amino acids when caloric requirements are met.


Our related articles


Organic food and farming

What we need to know about healthy diets

Healthy meal generator

External related articles

Low-Fat Vegan Diets By Sharon Palmer, RDN Today’s Dietitian

Learning Standards

Massachusetts Health Framework

Students will gain the knowledge and skills to select a diet that supports health and reduces the risk of illness and future chronic diseases. PreK–12 Standard 4

Through the study of Improving Nutrition students will
3.1 Identify the key nutrients in food that support healthy body systems (skeletal, circulatory) and recognize that the amount of food needed changes as the body grows
3.2 Use the USDA Food Guide Pyramid and its three major concepts of balance, variety, and moderation to plan healthy meals and snacks
3.3 Recognize hunger and satiety cues and how to make food decisions based upon these cues.
3.8 List the functions of key nutrients and describe how the United States Dietary Guidelines relate to health and the prevention of chronic disease throughout the life span.
3.9 Describe a healthy diet and adequate physical activity during the adolescent growth spurt.
3.20 Identify and analyze dietary plans, costs, and long-term outcomes of weight management programs.
3.21 Identify how social and cultural messages about food and eating influence nutrition choices.

Benchmarks for Science Literacy, American Association for the Advancement of Science

Increased knowledge about nutrition has led to the development of diets containing the variety of foods that can help people live longer and healthier lives. 8F/M7** (SFAA)

2016 Massachusetts Science and Technology/Engineering Curriculum Framework

HS-LS1-2. Develop and use a model to illustrate the key functions of animal body systems, including (a) food digestion, nutrient uptake, and transport through the body; (b) exchange of oxygen and carbon dioxide; (c) removal of wastes; and (d) regulation of
body processes.


The liver detoxifies your blood. “Almost all the blood in your body passes through the liver. As blood passes through the liver, it breaks down substances, such as prescription or over-the-counter drugs, street drugs, alcohol, and caffeine. Our bodies naturally produce some harmful (toxic) chemicals or poisons, and those are also broken down by the liver. In this way the liver acts as a filter to clean your blood.”


From US Dept of Veterans Affairs, “VA » Health Care » Viral Hepatitis » Veterans and Public Home » Liver Basics » Liver as Filter”

The liver produces bile, a kind of detergent that breaks up fat into small particles. Stored in the gallbladder, and then released when you are digesting a meal. Bile allows the body to digest fat.

The liver takes excess sugars, and links them together into a large molecule called glycogen. Liver then stores glycogen until energy is needed.

glycogen glucose

Image from National 5 Biology, nat5biopl.edubuzz.org

The liver makes cholesterol.


Kidshealth.org – Liver


Sample questions

Laboratory tests can be used to evaluate how well a person’s liver is working. One test measures how well the liver removes a substance called bilirubin from the blood. Based on this information, which of the following describes bilirubin?
A. an antibody
B. an energy source
C. a vitamin
D. a waste product

Learning Standards


Is evolution a theory or a fact

Is evolution a theory or a fact?

“evolution” has 2 different uses:
‘facts’ of evolution, and the ‘theory’ of evolution.

Here are observable facts

* Many forms of life that used to exist, no longer exist today.
(We’ve found many fossils; more are discovered every day)

* Many forms of life exist now, that did not exist in the past.
(Many modern animals and plants are obviously different from fossils)

* DNA exists.

* Every time an organism reproduces, random changes (mutations) in DNA happen. (We actually explicitly see these with gene-sequencing)

* Some mutations help an organism survive – those genes pass on to the next generation.
(We actually see organisms survive and reproduce. We can sequence the DNA of the parent and of the offspring. We literally see the genes.)

* Some mutations don’t help an organism survive; those genes die out.
(We actually see that some organisms die before they reproduce. Their genes literally die with them.)

* Millions of different DNA samples show a relationship between all forms of life.

* As time goes by, some genes become more common, some become less common. (This has been directly observed in bacteria, some plants and some animals)

Here is the theory that connect such facts

1. Organisms produce more offspring than can survive to adulthood and reproduce.

2. All organisms have random mutations.

3a. Mutations that allow an organism to survive are passed on to their offspring.

3b. Mutations that don’t allow an organism to survive die off.

4. So over time, some mutations become more common.

The “theory” of evolution is the relationship between observations (“facts.”)

In this sense, the theory is just as true as the theory of gravity, or the theory of electricity.



Evolution 101. Univ of California Museum of Paleontology



How do we know what DNA looks like

Question: How do we know what DNA and genes really look like?

We see images in books that look like this, but each individual atom is only a nanometer (1 x 10 -10 m) wide.

No visible light microscope can view objects made with such small pieces.



So the real way that we figured out the atom-by-atom structure of DNA is through a technique called X-ray crystallography.

Our molecule of interest – in this case, DNA – is concentrated and crystallized.

It is placed in front of an X-ray source.

The X-rays scatter off the DNA’s atoms. We capture this diffraction pattern on film (or on a digital X-ray detector.)

Photo 51 DNA Diffraction pattern

X-ray diffraction image of the double helix structure of the DNA molecule, taken 1952 by Raymond Gosling, commonly referred to as “Photo 51”, during work by Rosalind Franklin on the structure of DNA (text Wikipedia)

This diffraction pattern is beautiful but doesn’t directly look like the original molecule.

There is a mathematical relationship between the placement of the atoms, and where the atoms deflect – just like there is a relationship between hitting pool balls and how they deflect:

When you know how a pool table is set up, what balls are made of, and see how the balls move after being it, you could use math to work backwards to figure out where the balls originally where.

Billiards Pool

from Banks and Kicks in Pool and Billiards, Dr. Dave Alciatore, Billiards and Pool Principles, Techniques, Resources

Same here: We can use math to figure out what each individual atom in the DNA originally was.

In this image: X-rays leave a source; some pass through a lead screen

The X-rays hit crystallized molecules. X-rays bounce off of the molecules, and onto a film plate.

We end up with a diffraction pattern on film.

How does one physically interpret diffraction patterns in DNA?

DNA X-ray crystallography

Figure 11.4, Purves’s Life: The Science of Biology, 7th Edition

Once we have a diffraction pattern, we use math to work backwards, and figure out what the shape of the molecule must have been.

The result is an electron density map which almost exactly traces out the shape of the molecule.

Final step: tba

X Ray crystallography and electron density map

Left image: X-ray diffraction pattern, Wikimedia. Right upper image: electron density map. Right lower image: model fitting atoms to the density map.

Can we image DNA more directly?

Yes. One can use a scanning tunneling microscope (STM).) It shows detail at the the atomic level.  Along with the following image please read Livescience: DNA directly-photographed-for-first-time.html

Photo of DNA helix

DNA’s double-helix seen in electron microscope photograph. By Enzo Di Fabrizio, Magna Graecia University in Catanzaro, Italy.


Here is another STM image of DNA. You can see how closely it matches the model from X-ray crystallography.

STM image of DNA

External resources

Are there true pictures of the DNA molecule (not synthetic images), showing the double helix?

On DNA’s Anniversary: How Rosalind Franklin Missed the Helix

Sexism in science: did Watson and Crick really steal Rosalind Franklin’s data?.

Chromosomes in cells

You have 2 copies of every gene (one from each parent), so you must have 2 copies of every chromosome. The pair of the mom one and the dad one are called homologous chromosomes.

We can figure out where the genes are, on each chromosome.

Here is a rough map of some genes, found on homologous chromosomes.


Different forms of life have different numbers of chromosomes.

number of chromosomes in a species

Image from What’s a Genome, courtesy of http://www.GenomeNews Network.org/J. Craig Venter Institute. http://www.expeditions.udel.edu/extreme08/genomics/

Each chromosome contains many genes, so the total number of genes is huge.

Number of genes in a chromosome for each species

Image from What’s a Genome, courtesy of http://www.GenomeNews Network.org/J. Craig Venter Institute. http://www.expeditions.udel.edu/extreme08/genomics/

How many chromosomes are in a cell

Each organism has a characteristic number of chromosomes in a cell.

Humans have 46 chromosomes in almost every cell.

A karyotype allows us to extract them from a nucleus, and photograph them.

Then one can cut-and-paste each of the chromosome images, and line them up, to clearly show how we have 2 of each. Half are from one’s mother, and half from one’s father.