As a medical student I was taught many "facts" which have since proven to be false. Among them was the "fact" that "a calorie is a calorie is a calorie". Which is to say that, if a body consumes more calories than required, irrespective of the source of those calories (i.e. fat, protein, or carbohydrate), that body will accumulate fat. We know now that this is not exactly true.

The preferred energy source for the human body is glucose. Sugar. Other substances can be converted to energy, but not as efficiently. Glucose is readily obtained from all carbohydrate sources. These include most types of sugar (i.e. granulated sugar, fruit sugar (fructose), milk sugar (lactose) etc.) and all grains, root vegetables and other sources. Carbohydrate will not be wasted. Any excess is stored, first in the form of glycogen in liver and muscle cells, and then as fat.

The storage capacity for glycogen in liver and muscle is fixed and only enough to last a few days. The fat "tank", on the other hand, is remarkable in that its capacity to expand is almost limitless. The fat cell is called an adipocyte. Its precursor is called a pre-adipocyte. Pre-adipocytes have the ability to multiply and make more fat cells. When the fat cells are full, pre-adipocytes multiply and make more. So the storage facility continues to enlarge. In order for storage to occur, the hormone insulin must be present. In general, the more insulin present, the greater the amount of storage (fat).

For most of humankind's evolutionary history, the ability to store fat conferred a survival benefit during periods of famine. In modern times, however, with the availability of carbohydrate dense food 24/7, 365 days a year, this benefit is lost. Instead, it has created the so called "obesity epidemic" with all its associated medical conditions, morbidity and mortality.

Limiting the carbohydrate intake to below the individual's daily energy requirements forces the body to use its energy stores. First the glycogen in liver and muscle is used. This lasts only a few days. Less if the individual exercises. When the glycogen is used up, fat stores are utilized. Fat will continue to be burned 24/7 as long as the carbohydrate intake is below daily requirements.

Replacing the carbohydrate with non carbohydrate food does not significantly affect the fat loss. Animal fat, saturated fat (bad fat) intake is discouraged since it can adversely affect lipid levels, insulin sensitivity and cause other problems. Intake of "good fats" such as omega-3, omega-6 and olive oil, in moderate amounts is beneficial. 

Protein intake does not result in blood sugar elevation or accumulation of fat. If an individual alters their diet in such a manner that carbohydrate is reduced to below daily requirements and replaced by pure protein, weight (fat) loss will occur. This is true even if the total calories in the protein is greater than the carbohydrate calories would have been. It appears, therefore, that when it comes to how the human body utilizes energy sources, a calorie does NOT equal a calorie.

There are many low carbohydrate diets on the market. Each has its own biases, but carbohydrate reduction is key in all of them.

No diet should be undertaken unless your physician approves and monitors it. All diets, including low carbohydrate diets can be dangerous if an individual has certain medical conditions. For example, a low carbohydrate diet may be dangerous for diabetics on oral medication and/or insulin. It would require very close monitoring by a physician, and may be totally inappropriate in some cases. Other medical conditions must also be excluded before an individual is started on a low carbohydrate or any other type of diet.

Stay well. Stay safe.

Armando

E. A. Mastrangelo M.D. CAME, AME

I selected "The Checklist" as the title of this blog because I value checklists. To be embarrassingly honest, I am a bit of an obsessive compulsive. I believe that, to a certain degree, this is a good thing in many fields. We all hope that any individual we put our trust in (pilot, doctor, design engineer, etc.) pays close attention to details. An oversight, even a seemingly insignificant oversight, can have disastrous consequences. Checklists have been shown in numerous studies to greatly reduce the risk of “accidents”. They have proven invaluable in many fields including medicine, but were initially developed for use in aviation by pilots. Checklists enhance safety in a simple manner. They do not add complexity.

The following is a description of the birth of the checklist, adapted from chapter 2 of Atul Gawande’s New York Times Bestseller, The Checklist Manifesto. How to Get Things Right. It will also be found in numerous historical accounts of the event.

On October 30, 1935 at Wright Air Field in Dayton Ohio, the U.S. Army Air Corps held a flight competition for manufacturers vying to build the military’s next-generation long range bomber. Many felt it was only a formality. The Boeing Corporation’s model 299 was the superior aircraft. It could fly faster and farther than previous bombers with 5 times the bomb capacity requested by the military.

With a small group of Army brass and corporation executives observing, the sleek and impressive model 299 test plane with a 103 foot wingspan and 4 engines (versus the usual 2), taxied into position. It roared down the runway, smoothly lifted off and sharply climbed to three hundred feet. Then it stalled, turned on one wing and crashed. Two of the five member crew were killed, including the pilot, Major Ployer P. Hill.

The accident investigation concluded there was no mechanical failure. The crash was attributed to “pilot error”. This new plane was more complex than previous aircraft. The pilot was required to attend to multiple tasks including each of the four engines, retractable landing gear, wing flaps, electric trim tabs requiring adjustment to maintain stability at different airspeeds, constant speed propellers requiring their pitch be regulated with hydraulic controls, and more. While performing all these tasks, Major Hill forgot to release a new locking mechanism on the elevator and rudder controls. The model was deemed by many as “too much airplane for one man to fly”.

Even so, the army purchased a few from Boeing. Some insiders remained convinced that the airplane was flyable. A group of test pilots set about the task of finding a solution.

What they decided against doing is almost as interesting as the solution they came up with. They decided against longer pilot training. They reasoned that few pilots, if any, had more experience and expertise than Major Hill, the air corps’ chief of flight testing. But this new plane was too complicated to be left to the memory of any one person, regardless of experience or expertise.

The simple, yet ingenious, solution they did come up with was……the pilot’s checklist! They designed checklists for each phase of flight….take off, flight, landing and taxiing. They were simple, brief, to the point and short enough to fit on an index card.

As aircraft (and spacecraft) have become more complex, the checklists have become even more important. 

For those readers interested in a more detailed and in depth study of the impact checklists have had in all areas of human endeavour, I strongly recommend The Checklist Manifesto--How to Get Things Right (2009) by Atul Gawande.

Everyone has personal experiences and everyone has a story to tell. We learn from experience. When it comes to bad experiences, it is wise to learn from the experience of those who have gone before us and heed their advice. This is why pilots have adopted the use of checklists and others have wisely followed.

 If you would like to share your knowledge and experience with the community in general, and the aviation community in particular, I welcome your contributions.  

Stay well. Stay safe.

Armando