Diabetic Mediterranean Diet

In the U.S., our consumption of calories from sugar-sweetened beverages (SSBs) almost doubled between 1965 and 2002, now comprising 21% of our total calories.  (I’ve seen lower estimates, too, such as all added sugars accounting for 17% of total calories.)  Remember that our overweight and obesity rates started rising around 1970.  Any connection there?

Some have speculated that cutting back on SSB consumption would lead to loss of some excess weight.  But it’s never really been tested until now.

By the way, your typical sugary carbonated beverage has 145 calories of pure carbohydrate, most often high fructose corn syrup.  That’s equivalent to 10 tsp (50 ml) of table sugar.  Soft drinks are liquid candy.

Methodology

UNC investigators recruited  about 300 overweight and obese folks (average BMI 36, average weight 100 kg (220 lb), 84% female, 54% black) who drank at least 280 calories daily of caloric beverages (sugar-sweetened beverages, juice, juice drinks, sweetened coffee and tea, sweetened milk, sports drinks, and alcohol).  In other words, they all drank at least two soft drinks or the equivalent daily.  Participants agreed to make a dietary substitution for six months.

The participants were randomly assigned to one of three study groups with a hundred participants per group. For the next six months…

• Group WA substituted at least two of their SSBs daily with water (WA), any type as long as it was calorie-free.  Bottled water was provided.  This reduced sugary drink calories by 230/day.
• Group DB substituted at least two of their SSBs daily with calorie-free diet beverages (DB).  Beverages were provided.  This reduced sugary drink calories by 230/day.
• Group AC (attention controls) made no changes in baseline beverage consumption.  Investigators made a point not to talk to them about beverages.

All three groups had monthly group meetings.  WA and DB group meetings were focused on adherence to the beverage substitution guidelines.
The AC group meetings will involved a weigh-in and general weight loss information (e.g., read food labels, increase vegetable consumption, portion control, and increase physical exercise).

“All … groups had access to a group-specific …website, where they recorded the beverages (water and DB only) they consumed, reported their weekly weight, received feedback on progress, viewed tips, and linked to group-specific resources.”

Results

All three groups lost statistically significant amounts of weight, but there was no difference in amount of weight lost among the groups.  In other words, the folks who substituted water or diet beverages for  sweet drinks didn’t do any better than the AC (attentive control) group.

Average amounts of weight lost were in the range of 1.8 to 2.5% of total body weight.  For example, if you weigh 200 lb (91 kg) and lose 2% of your weight, that’s a 4-lb loss (1.8 kg).

Compared to the AC group, the WA group showed a statistically significant decrease in fasting blood sugar (down 3 mg/dl).  BTW, none of the participants were diabetic.

Take-Home Points

Would the substituters have lost weight if they had simply cut out two sugary drinks a day, skipping the monthy meetings and website?  Don’t know.  But I bet that’s how the mainstream press will spin this.

If I were obese and had a sugary drink habit, I’d start substituting water.  Yesterday.

Substituting water for a couple sugary drinks a day could reduce risk of developing diabetes.

I was hoping to see a significantly greater weight loss in the water and diet drink substituters compared to the AC (Attention Control) group.  Presumably all of these AC folks would have stayed at their baseline weights if they hadn’t done any of this.  The substitution groups apparently didn’t receive the general weight-loss information given to the AC group.

One caveat: All groups had monthly meetings for six months.  What were the substitution groups  talking about other than adherence to the protocol?  Your guess is as good as mine since the researchers don’t say.  Perhaps something about those meetings led to the weight loss, not the act of substituting water or diet drinks for sugar.

So they lost an average of 4–5 lb (2 kg).  Big deal, right?  But remember this was just a six-month study.  Could that 4 lb turn into 12 lb (5.5 kg) over 18 months?  Maybe, but we don’t know.

Here’s the thing about averages.  Some of these people I’m sure lost closer to 5% of body weight, and some didn’t lose any, or gained.  Which group would you be in?  Only one way to find out.

Remember that many medical conditions linked to overweight and obesity improve with loss of just 5% of body weight.

The substituters cut out 230 calories a day of sugary drinks.  All other things being equal, they should have lost 12 lb (5.5 kg).  Problem is, all other things aren’t equal.  Numerous other factors are at play, such as activity levels, replacement of sugary drink calories with other calories, measurement errors, reporting errors, etc.

This was a female-heavy study.  Would this strategy work for men?  Even better in men?  We don’t know.  Why not try it yourself?

Steve Parker, M.D.

PS: I did a sugar-free and wheat-free experiment on myself earlier this year.  Lost some weight, too.

Reference: Tate, Deborah, et al.  Replacing caloric beverages with water or diet beverages for weight loss in adults: main results of the Choose Healthy Options Conscioulsly Everday (CHOICE) randomized clinical trial.  American Journal of Clinical Nutrition, February 1, 2012, Epub ahead of print.  doi: 10.3945/ajcn.111.026278