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Archive for February, 2010

Food Rules and Food Journals: a Healthy Match

February 23rd, 2010

I just enjoyed reading Michael Pollan‘s new mini-book entitled Food Rules: An Eater’s Manual.  I will save you yet another review of the book—Instead, I’ll just mention that it is always helpful to have a two-hour refresher course in age-old common-sense eating practices.

Pollan’s book is divided into three sections, based on his oft-quoted mantra: “Eat food.  Not too much.  Mostly plants.”  Among the sections, there are 64 two-paragraph rules of thumb, including:

  • “Don’t eat anything your great-grandmother wouldn’t recognize as food,”
  • “Shop the peripheries of the supermarket and stay out of the middle,”
  • “Eat only foods that will eventually rot,”
  • “Eat mostly plants, especially leaves,”
  • “Don’t overlook the oily little fishes,”
  • “Eat all the junkfood you want as long as you cook it yourself,”
  • “Buy smaller plates and glasses,”
  • “Server a proper portion and don’t go back for seconds,” and my favorite
  • “Break the rules once in a while.”

Pollan is careful to not come off as dogmatic or prescriptive: as you can see in the last rule of his book, following the rules includes breaking the rules, as long as you are conscious of how you break them and how often you break them.

Given how short Food Rules is, it is worth the read.  Before jumping into the book, however, equip yourself with tools that will help you gauge yourself.  Spend a week building a food journal in PhotoCalorie.  Once you have a record of your eating habits, take the quick read through Pollan’s book.  If you find any inspirational rules, take a quick look at your food journal for the past week: do you see anything concrete in the pictures you took that you would like to do more of or avoid in the future?  After completing the book, spend the next week reflecting as you keep your PhotoCalorie food journal.  Hopefully, combining the rules with a regular food journal can help you move toward or maintain a healthy diet.

Nutrition and Weight Loss, iPhone app

Eating Carbs Before a Workout Dramatically Decreases How Much Fat You Burn

February 1st, 2010

Ever wondered what to eat before heading to the gym for your daily workout? The answer to this question depends on what your goal is as well as who you ask. Looking to run the next Boston marathon? You should probably eat a balanced meal, high in complex carbs, to try to build up your stored glycogen. But for the rest of us, does it even matter what we eat?

Before we answer this question, we must first review some basic physiology. Let’s look at carbohydrate metabolism. When a person eats carbs, whether they drink a Coke or eat some brown rice, the starches and sugars are broken down into glucose, eventually increasing the glucose present in your blood. Cells all over the body can use this glucose for energy and nutrition. Shortly after this spike, your pancreas notices this change in blood sugar and releases a hormone called insulin, which essentially causes the liver, muscle and fat tissue to take up the glucose, and brings the blood sugar back to healthy levels. The speed with which this happens is based on the glycemic index of the food, which measures the effect of carbohydrates on blood sugar. Coke would cause a larger, more immediate rise in blood sugar, leading to a speedier release of insulin. Brown rice on the other hand, has a lower glycemic index. The glucose would enter the blood stream at a slower rate, leading to a more gradual release of insulin. Protein also leads to an increase in insulin, but to a much smaller extent.

When insulin is released, the body goes into storage mode. Glucose from the blood is being stored in your fat cells, your liver cells, and your muscle cells. This is precisely the opposite of what you want to happen in your fat cells while you are exercising. Ideally our fat cells will release their stored energy into the blood stream as fatty acids and glycerol. The fat cells  would shrink in size, causing us to shrink in size as well.

In an article published last month, German researchers tested this hypothesis. They looked at the effect of exercise during a fasting state and 30 minutes after a carbohydrate-rich or protein-rich meal. During each scenario, the researchers measured the blood glycerol and insulin levels in each subject. As illustrated in the figure below, when the subjects ate bread 30 minutes before exercising, their insulin spiked, inhibiting the fat cells from being broken down and used as energy (the line with solid squares). When they ate pork 30 minutes in advance (line with empty triangles), there was also an insulin spike, but a much smaller one.

The researchers explained the results saying fat cells being broken down during exercise is “virtually abolished by a small carbohydrate-rich meal when ingested shortly before exercise.” In summary, to burn the most fat during moderate intensity exercise, try not to eat anything a few hours before you head to the gym, but if you do eat, stay away from those Cheetos!

You can use PhotoCalorie to help monitor this. If you exercise around the same time every day, check out your journal to see if you have been eating carbs right before your workouts, as they can decrease how much fat you burn while you are exercising, and may lead to less weight loss overall. Hope this helps you lose weight more efficiently!

Exercise