Dr. Oz's Diet Advice

I was really bored yesterday, August 6, 2012.  Flipping through the channels, I came upon the Dr. Oz show, and I wondered what woo he was pushing today.  Sure enough, he begins the show with metabolism boosters.  

I immediately began to wonder whether a person can really boost their metabolism by simply drinking tomato juice spiked with a little Tabasco sauce and lime juice, but then he said this.

"And while wine snobs may not approve, adding ice chips to your red wine forces your body to burn calories, as it has to use its own energy to warm the liquid to body temperature."

Let's see what science has to say about this.

One learns in both physics and chemistry courses that to raise the temperature of any substance it takes an amount of energy equal to Q = mcdT where m is the mass of the substance, dT is the final temperature minus the initial temperature, and c is called the specific heat. The specific heat takes into account all the complicated physics and chemistry of how energy is distributed among the atoms and molecules.

I went to my freezer and looked at a ice cube - technically it's not a cube, it's a rectangular solid, but I'm being pedantic.  I don't have a kitchen scale, so I'll determine its mass by measuring its dimensions.  My cube is 5 cm by 3 cm by 3.5 cm or about 53 cm³.  The density of ice is 0.998 grams per cubic centimeter, so I can calculate its mass by multiplying the density by the volume.  Therefore, my ice cube's mass is 53 grams.

The ice will melt and cool the wine as cold as 0ºC.  After you drink the wine, your body will warm the liquid to body temperature, about 37ºC.

The specific heat of water is 1 calorie per gram per Celsius degree.  So your body will use 

Q = (53 g)(1 cal/(g ºC))(37ºC–0ºC) = 1961 calories.

But I have to correct something here.  A food calorie is different from a calorie.  A food calorie, also called the Calorie (notice the capital C), is equal to 1000 calories.

So your body has to expend almost 2 Calories to warm the cold wine.  I think you can burn 2 Calories by breathing for a whole minute.

UPDATE: Oops! I made a mistake here.  Your body has to warm all the liquid, not just the melted ice.  If you have a standard serving of wine, 6 oz., then your body expends 8.5 Calories.

You can do a little better by eating the ice, since your body has to melt the ice, too.  I''ll spare you the details, but that takes a whopping 4 10 Calories! Assuming you drink the wine, too.

Even if you live a sedentary lifestyle, you will burn at least 1200 Calories every day by just existing. This is your metabolic activity. If you are active, your metabolic activity can be as high as 3000 Calories.  

If you want a little dieting advice, I share with you the only diet proven to work.  

The Thermodynamic Diet

The 1st law of thermodynamics states that one cannot create nor destroy energy.  All that can be done is to convert energy from one form to another.  Your body converts chemical energy in the food to kinetic energy (energy of motion) and thermal energy (you may call that heat, but that's technically incorrect).  Any energy not converted into these two forms may be converted into another form of chemical energy; that is, weight gain.

So the thermodynamic diet is burn more calories than you ingest.

Teens These Days

Have you seen the news reports about teens playing the "Salt & Ice" game?  It involves sprinkling table salt on your skin, and then putting an ice cube on top of the salt.  You then are supposed to press down on the cube until the pain is too much to bear.

What's scary about this is that serious tissue damage can result.  Frostbite is a real possibility.  With frostbite, "ice crystals form in the space outside of the cells. Water is lost from the cell's interior, and dehydration promotes the destruction of the cell."*

Furthermore, "as blood flow returns to the extremities upon rewarming, it finds that the blood vessels themselves are injured, also by the cold. Holes appear in vessel walls and blood leaks out into the tissues. Flow is impeded and turbulent and small clots form in the smallest vessels of the extremities. Because of these blood flow problems, complicated interactions occur, and inflammation causes further tissue damage. This injury is the primary determinant of the amount of tissue damage that occurs in the end."*

Now that I've dealt with the biology, let's discuss the physics.

You learn in your science class that water freezes at 32ºF (0ºC).  Now that's really only true for pure water.  Dissolving any substance (salt, sugar, alcohol, antifreeze) in water will lower the temperature at which the solution freezes.  A solution that is 23.3% salt by weight will freeze at -6ºF (-21ºC).

Here's what happens in the "Salt & Ice" challenge.  The ice cube coming from a typical freezer may be at a temperature of 0ºF (-18ºC).  Since it's in contact with your skin, some ice melts.  The water that results is at 32ºF (0ºC), but it mixes with the salt.  Since the salt-water is in contact with the ice cube, the water cools down to the temperature of the cube.  

Let me repeat that last point.  The salt-water is at a temperature as low as 0ºF (-18ºC).  

It's the cold water that poses the danger here.  It takes a relatively large amount of energy to change water's temperature.  Scientist call this thermal property the specific heat.  So energy is being transferred from your skin to the salt-water, your skin cools drastically, and the salt water barely changes temperature.  In fact, the salt-water really doesn't change temperature at all, since it's still in contact with the ice cube.

We can use this physics we have have friends over for grilled meat.  If you happen to forget to cool off the beer, add the drinks and ice to the cooler.  Then pour in some water and some salt.  You'll have cold beer in no time.  The only way to get it colder and faster is with liquid nitrogen, but that can be a little hard to come by.

*http://www.emedicinehealth.com/frostbite/article_em.htm