Archive for May, 2009

High Fructose Corn Syrup

What’s the verdict?  Studies are still up in the air.  Check out my recent post about this on Martha McKittrick’s blog.  Or read it right here:

If you live in America and eat her food, chances are you’re consuming high-fructose corn syrup (HFCS).  A quick look around the grocery store reveals plenty of products with this ingredient.  Fructose is the sweetest and cheapest of all sugars, making it convenient and desirable to manufacture.  For this reason, it’s used in most packaged foods.

What exactly is HFCS?  And is it really that unhealthy?
Although fructose is a type of sugar found naturally in fruit, it is modified radically when it becomes high-fructose corn syrup.  U.S. corn refiners produce HFCS by converting corn starch to syrup (they have to do this because glucose is the type of sugar in corn, not fructose!)  The syrup is then treated with a series of synthetic enzymes and additives. The result is a mix between fructose and glucose, and a treasure trove of HFCS is born for food manufacturers to use at their disposal.

What are some products that have HFCS?
Almost all processed (convenience) foods and sodas have HFCS.  Even unsuspecting foods will have this sugar.  Here are some examples:

• Dannon light yogurt
• Gatorade
• Salad dressing
• Ketchup
• Soda
• Chocolate syrup

What’s the verdict?
Many studies show a link between obesity and sweetened drinks, which have HFCS.  On the other hand, the American Medical Association (AMA) recently concluded that high fructose corn syrup “does not appear to contribute more to obesity than other caloric sweeteners.”  Clearly, the reports are still unclear!  But conclusive new evidence this year proposes that not all sugars are created equal.  The study, in the Journal of Clinical Investigation, compared how our bodies respond to glucose and fructose.  University of California Davis researchers found that those who drank fructose-sweetened beverages showed negatives changes in liver function and fat deposits.

Should I Stop Eating High-Fructose Corn Syrup?
In vast quantities, yes.  Food and beverages processed with this sugar are usually empty calories (meaning, that they provide little nutritional value!)  Regularly incorporating foods with HFCS can also lead to greater risk chronic diseases like diabetes, heart disease and obesity.

Here are some practical tips:
1) Curb your processed food enthusiasm. Those trying to stick with unprocessed foods and/or organic ingredients should also avoid HFCS.

2) Fructose from fruit and vegetables is okay! Remember, fructose is natural. HFCS is not, being that the enzyme preparation is synthetic.

3) Sugar is sugar is sugar.  Whether in the form of glucose, table sugar, fructose HFCS or even honey, the amount of total sugar intake is what matters.

4) Choose products with no added sugar. And make sure to check the ingredient list, just to be sure.

5) Be skeptical. The Corn Association just put out commercials attempting to dismantle HFCS’s bad rap.

6) Balance it out. As with other food, HFCS can be enjoyed in moderation.

References:  http://www.time.com/time/health/article/0,8599,1892841,00.html
High Fructose Corn Syrup and Weight Status, Dec 2008. ADA position paper

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Calculate Your Own Energy Needs

Oftentimes, we over or underestimate how many calories our bodies require per day.  It’s difficult to figure this out because our energy needs vary on a daily basis, depending upon activity level.  Dietitians will plug in height, weight, age and gender into certain equations in order to figure out Basal Metabolic Rate (BMR),  a measurement of how many calories the body burns at rest.  There are a few different equations that can be used, as well as numerical coefficients for general caloric ranges.

The Harris-Benedict equation for BMR:

  • For men: (13.75 x w) + (5 x h) – (6.76 x a) + 66
  • For women: (9.56 x w) + (1.85 x h) – (4.68 x a) + 655

The Mifflin-St. Jeor equation for BMR:

  • For men: (10 x w) + (6.25 x h) – (5 x a) + 5
  • For women: (10 x w) + (6.25 x h) – (5 x a) – 161

Where: w = weight in kg, h = height in cm, a = age

This does not take activity into account, and so the final number needs to be multiplied by an activity factor of 1.2-2, depending upon how active the individual is.

~sedentary (little or no exercise) = BMR x 1.2

~lightly active (light exercise/sports 1-3 days/week) = BMR x 1.375

~moderatetely active (moderate exercise/sports 3-5 days/week) = BMR x 1.55

~very active (hard exercise/sports 6-7 days a week) = BMR x 1.725

~extra active (very hard exercise/sports & physical job or 2x training) = BMR x 1.9sunlight

Coefficients for Caloric Ranges:

In a clinical setting, we use coefficients to make it easier and faster to calculate ranges for patients.  For normal weight (BMI between 18.5-24.9), the coefficient is 25kcal/kg – 30 kcal/kg.  For overweight to obese, one can either decrease the coefficient to 20-25kcal/kg or create an ADJUSTED BODY WEIGHT (ABW) and multiple the ABW by a normal coefficient, 25-30kcal/kg/body weight.  For underweight individuals, or those with hypermetabolic needs, the coefficient can be as high as 30-35 kcal/kg of body weight.

It’s necessary first to find out what your IDEAL BODY WEIGHT (IBW) is, which is not necessarily an ideal body weight FOR YOU, but just a general reference +/- 10% based on gender and height.  It is usually on the low side, and so adding 10% is recommended and still within normal limits.

To find an IBW:

1.  Take your height in inches and convert it to centimeters (conversion factor: 2.54). Example, 5’5″ = 65inches.  65 x 2.54 = 165.1cm.

2. Calculation:

For women, it is 100 pounds for the first 5 feet, and 5 pounds per every inch over 5 feet.  Clearly, this is low if you are on the muscular side.

For men, it is 106 pounds for the first 5 feet and another 6 pounds per every inch over 5 feet.  Muscular men will need to factor in at least +10%.

So then, a 5’9″ male’s ideal body weight (+/- 10%) would be: 100 + (9 inches x 6) = 154 pounds. Remember that extra 10%, 154 lbs + 15.4 = 169.4 pounds, which is a nice ideal body weight.

To find an ABW:

The adjusted body weight (which is a body weight that becomes a goal weight in overweight and obese cases, and the one we use to calculate caloric needs), the formula is: current body weight  – ideal body weight =  “X.” Then, take “X”  x  .25 = “Y.”  Then, take “Y” + ideal body weight  = adjusted body weight.

EXAMPLE:

Let us use our example male of 5’9″ above. Let’s pretend his name is Kevin, he’s 28 and overweight with a current body weight (CBW) at 200 pounds.

200 (CBW) – 154 (IBW) = 46.

46 x .25  = 11.5.  11.5 + 154 (IBW) = 165.5

(note: this is very close to just adding 10% to his IBW).

Now lets divide 165.5 by 2.2 to get Kevin’s adjusted body weight in kilograms. This would be: 75.2kg.

For a kcal range per day, we multiply Kevin’s adjusted body weight in kilograms by 25 for the lower range, then 30 for the upper. Here is his kcal range:

1880 – 2256 kcal/kg/adjusted body weight

For protein range, we multiple his adjusted body weight in kilograms by 0.8 for the lower range, and the 1.2 for the upper.  Here is his protein range in grams/day:

60gms – 90gms/kg/adjusted body weight

For fluid needs in mL, just multiple his current body weight (in kg–> 200lbs = 91kg) by 30 for the lower and then 35 for the upper (it’s important to stay within the fluid range, too). So this would be:

2700mL – 3150 mL/kg/CBW per day. (This is roughly equal to 13 cups per day)

Now let’s compare our range to the Mifflin St-Jeor range to see how accurate we are (we are still using his ABW, since we do not want Kevin to maintain his weight, but rather, lose it):

For Kevin, the Mifflin equation states that his needs would be: (10 x 75.2kg) + (6.25 x 175.3cm) – (5 x 28years) + 5 = 1712kcal/day, which, when we apply an activity factor of sedentary (little or no exercise) = 1712 x 1.2 = 2054, which is right in the middle of the range we supplied for him above (1880 – 2256).

Now that we know our estimate is in line with the Mifflin equation, let’s see if it is appropriate for healthy weight loss.  Using the Mifflin equation, let’s plug in his CBW of 90kg.  Kevin needs 2140kcal/day to maintain his weight.  For him to LOSE 1lb per week, we need to subtract 3500 kcal/week from his diet, since 3500 kcal = 1 pound.  2140- 500kcal/day = 1640.  1640 is close to the lower range that we deduced (1712), meaning that we would recommend around 1700 kcal/day for Kevin to lose 1 lb per week.

Train Low, Compete High

It’s controversial.  Imagine rowing, running or swimming your heart out and recovering with a nice bowl of… salad.  Not too enticing.  And it probably feels horrible.  Yet new research suggests that endurance is enhanced when training in “a glycogen-depleted state.”  They’re calling it “train low, compete high,” referring to the nutrition component of training.  By intentionally under-fueling muscles during training, there might be a better ability to use fat more efficiently for energy and spare glycogen for later.

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Glycogen is the body’s energy reserve that is topped off with carbohydrate-rich meals.  Coaches will therefore recommend consuming carbs (in beverage, gel or food form) before and during exercise to ensure enough energy for the event.  It’s like an ATP piggy bank.  With lower glycogen, metabolism shifts to muscle and fat oxidation.  The theory is that training at this lower glycogen state will improve fat oxidation over time so the athlete can maximize her energy during competition.

More research needs to be done on this concept, which has only been reviewed with regards to lower intensity training.  I cannot imagine training for a long period of time on, essentially, a low carbohydrate diet.  I am assuming that the athletes have to ingest higher percentages of fat and protein as compared to the RDA.