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December 12, 2012 / jeremycarr

Science of Nutrition- Part 2

In part 1 we explored how different nutrients are important for your diet.  In part 2, we explore the link between nutrition and energy.

Feeling Less Hungry
I wanted to start with the elephant in the room: losing weight. I wouldn’t mind losing weight, and generally speaking “Calories out – Calories in = change in weight”. Plug in a few helpful facts and I had the recipe for weight loss: the average person burns 2000-2500 calories/day at rest, and the energy to lose a pound is ~3500 calories. But what does this mean practically? To lose weight via dieting, it’s a simple matter of eating less calories than I burn off. This unfortunately seems like a recipe for being hungry all the time, which implies unsustainability, lower quality of life, and eventually binge eating/falling off the diet. So first thing’s first- how can I feel satiated while minimizing calories?

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Satiation immediately after eating

Feeling full immediately after eating is largely a function of the physical volume of food eaten. Most high volume/low calorie food is high in water and/or low in fat- vegetables, fruits, etc. Consider eating 50 calories via a cup of strawberries, or 1 donut hole- it’s easy to imagine which would be more filling.  Put another way, I would have to eat at least 20 pounds of spinach to meet my daily caloric needs!  Drink a lot of water and include a large volume of low caloric density food in my meals.  Check.

Satiation a few hours after eating
Feeling less hungry is complicated.  Our bodies process the energy of different foods at different rates.  A simple guideline is foods with a low glycemic index (more below) typically digest slower and help the body to burn energy over a longer period, making us less hungry.  Foods high in protein, fiber, and water such as fruit, oats, beans, lean meat are great starting points towards not feeling hungry.

Energy Levels
Many factors influence energy levels beyond nutrition including energy, sleep, and stress. Specific to nutrition, blood sugar levels are critically important. When we have low blood sugar (ie- haven’t eaten in awhile), the body doesn’t have enough raw energy to function and so we feel tired. On the opposite end of the spectrum eating high glycemic index foods causes a spike in blood sugar, which leads to overproduction of insulin, which metabolizes the sugar and results in low blood sugar, causing a sugar crash.

I was shocked with the effects of making a conscious effort to eat low glycemic index foods and not overeating; within a day I actually felt significantly more energetic and stopped suffering from afternoon drowsiness. Rock!

Caloric Sources37Nutritionals

Countless gallons of ink have been spilled on the eternal debate swirling around calories. Different types, different sources, pros and cons… The most helpful advice I found was pretty simple: eat a balanced diet. There are no miracle or devil foods. Only a spectrum of different foods, and moderation is the prognosis.

Understanding sugar is the key to understanding carbohydrates. Carbohydrates are typically simple (sugar) or complex (starch, fiber). Simple carbohydrates (fructose, white grains) are processed by the body quickly, don’t fill you up, and play havoc on energy levels by causing sugar high/sugar crash. Starch (glucose) is a more complex form of sugar, requiring the body to expend more effort breaking it down. Fiber is the fundamental balancing force to sugar; foods high in fiber slow down the digestion and absorption of carbohydrates and prevent rapid increases in blood sugar levels. Our old friend the glycemic index is a helpful metric to measure the rate at which carbohydrates will be digested; here are a few examples of low glycemic foods that provide more consistent energy over time.


Protein is generally great for you since it builds muscle, has high satiability, and provides your body with essential amino acids. One thing to be mindful of is since protein is most often sourced from meat, it’s oftentimes paired with bad fats. This is why protein sources such as soy, beans, seafood, and lean cuts of meat make it easier to stay out of trouble.


Fats are calorically dense at 9 calories/gram, while carbs and protein are 4 calories/gram. There are 4 main types of fat. Mono-unsaturated and poly-unsaturated fats are healthy because they contain nutrients needed to be healthy while having no (poly) or positive (mono) effects on cholesterol.  Saturated fats are widely misunderstood, but typically on the unhealthy side because they tend to raise my LDL cholesterol.  It’s hard to make an argument that trans fats are anything but bad for me.

Putting it all together269405_986864754990_151610540_n
I want low calories (portion size, caloric density), but to feel satiated (fiber, protein) and have consistent energy (glycemic index, avoid overeating).

Goal: Low calories + feeling satiated + consistent energy

This means I will focus on having a protein and fiber rich carb diet, while avoiding bad carbs and bad fats.  Practically speaking this means I’ll be eating a lot of vegetables, fruits, legumes, lean meat/seafood, and whole grains.  Meanwhile, I’ll be reducing sugary foods, red meat, and fatty foods in general.  Roughly speaking I aim for a caloric distribution of around 10% fat (low), 30% protein (high), and 60% carbohydrates (standard).  I certainly am not going to be militant about my diet, but since even a single heavy meal will punish me with a food coma, I have a helpful guardrail to stay on track.

Lessons Learned

  • The healthiness of food is on a spectrum.
  • Eat food. Not too much. Mostly plants. –Michael Pollan
  • There’s no silver bullet.  Eat a balanced diet; no evil or blessed ingredients.


Leave a Comment
  1. Sandy / Dec 12 2012 1:39 pm

    This is great! I think most of us are more concerned with quality of life than weight. We just don’t often relate energy levels to diet.

    I’d put a star on the drink more water, especially if you’re a caffeine addict. I keep a can of water at my desk for convenience.

  2. Ted Durant / Dec 13 2012 7:35 pm

    You need to get past the NIH to get the whole story.

    • Jeremy / Dec 14 2012 1:40 pm

      Thanks for the comment Ted! Mark’s article is indeed an excellent explanation of saturated fat, and I edited the post to soften the overly strong claim that “saturated fat is bad”. Pragmatically- when evaluating saturated fat against my three goals, I’ve found that saturated fat typically makes me feel sluggish, and comes with a lot of caloric baggage. Regardless of satiation, the energy effects alone are enough for me to minimize my intake.

  3. Myles Andueza / Feb 3 2013 6:39 pm

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  1. Science of Nutrition- Part 1 « Simple Chaos

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