Hello and welcome. I’m Doctor Clyde. I have taught this course every year for Stanford Continuing Studies since 2008. The course used to be called “Food Facts Versus Fads” as a simplified version of the medical school course I taught at both Stanford and UCSF called “Food Facts, Fads, and Pharmacology.” 

There are two things I have learned about nutrition over my years of teaching that surprised me the most. The first is that every crazy diet has at least a small grain of truth within it. This means every diet is “correct” to an extent (within some context) despite being very different (or even the opposite) of some other diet that is equally correct. The key to finding what works best for each of us as individuals therefore lies in discovering the universal truths underlying all dietary patterns simultaneously. It is the universal truths that best serve as a starting point for each of us to discover our own unique nutrition strategy.

The second surprising thing I came to realize was that healthy nutrition requires more than simply eating healthy food.  Salad is healthy, but it might not be giving you enough of everything you need.  Drinking more water or having almonds as a snack might not either. Achieving goals requires providing enough of each thing your body needs to keep it working properly. A healthy diet therefore requires us to think about how the body works and what we might be missing. Like a car, it only takes one problem (such as a faulty engine part, a flat tire, or an empty tank) to create a bottleneck and therefore keep the entire system from functioning.  By fixing only what needs fixing (and nothing else), both your car and your body can hum along smoothly.  If you ignore or don’t know what is wrong with a system, you might go on indefinitely struggling in an uphill battle that goes nowhere.

I was born with elevated metabolic disease risks, later becoming obese with high blood pressure. These issues led to my quest to discover the universal truths that underlie our metabolism in a practical sense that I could take action on. I knew that a deeper understanding of how the body worked was the only way to overcome the disaster of the Calorie model that tends to promote excessively cutting out food groups, food portions, or both until the body shuts down even more than it already had been. In my twenties, in nuclear engineering on an aircraft carrier in the US Navy, my doctor suggested I find a good book on nutrition to lose weight and get healthier. That is when I first encountered what was not only different but opposite perspectives on how to eat. Rather than getting a book that lured me into one or another belief system, I re-engaged with my rational common sense to make better choices. My doctor was shocked at the results; he had never seen such a rapid improvement. Rational thinking had kept me from having to go on meds. What surprised me even more was the dramatic increase in my powerlifting strength that emerged from eating healthier. A dozen years later, I got my PhD in chemistry and started teaching common-sense nutrition at Stanford.

The more I taught, I more I realized that our body is a system, just like the nuclear reactor plant on the ship that creates steam from fission to turn a propeller and launch jets. It has taken me a quarter century and teaching over 100 classes to simplify what our cells need into a nutrition model that shows how to adjust any dietary pattern by discovering its bottleneck, just like fixing a car. What has taken me a lifetime of rumination and research has circled me back to how our great-grandparents naturally lived their lives and what Hippocrates recognized over 2,000 years ago, which is that health derives from moderation in all things and that healthy food is medicine. Unfortunately, the prevalence of processed food and fad diets have created a confusing nutrition environment that derails our common sense. To recover it, we need a rational model of how to eat that takes into account the truths within the chaotic perspectives competing for our attention. That is the purpose of this course.

Although healthy eating comes down to a balance of unprocessed foods evenly spaced throughout the day, for many, this simplicity is no longer sufficient to succeed without a rational model to guide them. A rational model for how to eat is necessarily based on how the body works. Since the body is complex, the model must be built on the principle of Einstein’s paraphrased quote to “keep things as simple as possible, but no simpler.” We want just enough complexity, without any extra, to efficiently and sustainably achieve our health and fitness goals.

I appreciate your joining me on this journey to discover your best health and fitness as a basis for achieving your best life experience. It is not an exaggeration to say our experience as living organisms depends on our physiological and psychological function, and that both of these depend on our nutrition.

For those listening to the audio, these course notes are read by computer versions of my voice alternating with our “metabolic mascot” created and voiced by my 10-year-old daughter Maya. This mascot is cheering us on to achieve our metabolic goals, which include longevity, healthy weight loss, healthy weight gain, fitness, or any combination of these.  Maya visualizes Little Metabolic as a happy gene, meaning a snippet of DNA smiling as it holds out a heart in friendship. You will hear Little Metabolic and me alternating as we go along.

Here are a dozen terms helpful to our discussion on how the body works, read by myself and “Little Metabolic” in the audio:

A.  Hello, this is Little Metabolic! DNA is our genetic code, which is a series of genes strung together in a row.

B.  A gene is a short segment of our DNA that encodes for one protein.

C.  RNA is a copy of a gene, meaning it is the genetic code for one protein. RNA is used by the protein factories in cells called ribosomes to assemble amino acids in the correct order for whatever protein they are making.

D.  Adenosine Tri-Phosphate or “ATP” is the energy molecule created in our cells using the oxygen we breathe and the food we eat. A steady supply of fats and blood sugar to our cells from healthy balanced eating accelerates protein production by accelerating the ATP fuel supply to the ribosome protein factories.

E.  The endocrine system consists of the organs that release hormones into the bloodstream.

F.  Hormones are signaling molecules that give the cells throughout our body instructions. 

G. Insulin is the hormone released when we eat, telling our cells to absorb Calories. Insulin is released in large amounts in response to either overeating or to fast-digesting carbs (even when not overeating). A large insulin release increases body fat by telling fat cells to 1) absorb and store Calories and 2) release less fat into the bloodstream for fuel because there are enough Calories in the bloodstream already. Most of the weight gain from repeatedly stimulating excess insulin occurs from your body holding onto its stored fat.

H.  Cortisol is a hormone that breaks down muscle in response to nutrient, mental, or physical stress, including the stress of exercise. Muscle loss reduces metabolism and fat burning, thereby increasing body fat.

I.     Amino acids are the building blocks of protein. When amino acid levels are low in the blood circulation, the brain stimulates cortisol release to break down muscle protein to provide amino acids to more vital organs.

J.   Carbohydrates generate energy 3 times faster than fat burning, making them essential for nerve signaling and intense muscle contraction. When blood sugar gets low, the brain stimulates cortisol release to break down muscle so amino acids can be converted into glucose by the liver to keep the brain functioning.

K.  Lipids are fats, including fatty acids and triglycerides for slow energy production, as well as cholesterol.

L.   Metabolism is the active burning of Calories to drive the molecular and cellular functions of living systems. Metabolism, therefore, underlies our subjective physiological and psychological vitality. Our metabolic rate refers to the rate we burn Calories, both carbs and fats, and contributes directly to our health and fitness.

The metabolic goals of healthy sustainable weight loss, weight gain, health span, and fitness are achieved by maintaining or building muscle mass while avoiding or reducing body fat. This is why maintaining relatively low insulin and cortisol levels at the same time is central to achieving health and fitness goals. Overeating at any one time results in a large insulin response (overflowing calories into lipid storage) whereas undereating or fasting raises cortisol (breaking down muscle as the body eats itself). Flip-flopping between large meals (eating whatever you want) and then skipping meals can create a vicious cycle of combined muscle loss and lipid accumulation that accelerate each other over time. This has led to the research findings that people who skip breakfast can end up burning more muscle than fat and increase their risk of cardiovascular mortality by 40%. Avoiding this requires eating a balance of unprocessed natural food evenly throughout the day as the body needs it.

A balance of unprocessed natural food in moderation digests slow enough that muscle can absorb and use the nutrients that would have overflowed into fat if it had digested faster. This effectively nourishes our muscle by starving our fat. Processed carbs do the opposite, failing to keep either insulin or cortisol low. Because they digest fast, processed carbs result in a large insulin response that rollercoasters blood sugar down as it overflows to fat. This raises cortisol to break down muscle to bring it back up. These hormonal dynamics are why we can’t just eat whatever we want half of the time (leading to high insulin) and then not eat at all the other half (leading to high cortisol).