Should you Swap Your H20 for Diet Pop?

Posted On Jun 3, 2014 By Erin Kuh, MBA, RD

deit soda or water for weight loss

Until this past week, most headlines screamed that diet sodas offer no benefit over regular soda, contribute to weight gain and have other harmful effects like causing cancer, increased risk of stroke and Alzheimer's disease. They should be avoided at all costs, if you follow headlines. But now that's all changing due to a recent study showing diet soda might, in fact, help with weight loss.

The Study

In the Journal of Obesity, a study following a group of 300 people for 12 weeks, the results showed diet-soda drinkers lost 13 pounds and water drinkers lost 9 pounds. The results seem straightforward: trading regular soda for diet soda cuts calories and sugar, aiding in creating a calorie deficit necessary for weight loss. But based on this, wouldn't switching to water yield the same results? It appears, according to the study, that this isn't the case.

The diet-soda group also reported feeling less hungry and had improvements in cholesterol levels. On the surface, the stats seem reliable, but let's dig a little deeper to determine why the diet-soda drinking group lost an average of 4 pounds more than the water only group.

Dr. Jim Hill, who helped author the study, brought up an interesting explanation for why the diet-soda group lost more weight. "The most likely explanation was that having access to drinks with sweet taste helps the (artificially sweetened beverage) group to adhere better to the behavioral change program," said Hill. He acknowledged that the diet soda itself wasn't responsible for the additional 4 pounds.

In other words, the diet-soda drinking group didn't have to make as many changes or practice quite as much willpower as the water only group. They could have had an easier time overall in focusing on calorie reduction or regular exercise knowing that they could have diet soda. The water group didn't have this vice to fall back on, making it more difficult to adhere to all of the other healthy habits, like food logging and regular exercise, they did during the study.

A few more points to ponder

  • What about the caffeine in diet soda? This could have suppressed hunger or given participants a jolt of energy to help exercise harder or eat less, creating a greater overall calorie deficit. The same thing might be achieved by drinking coffee or tea.
  • What about the carbonation? Usually fizzy drinks make you feel full, regardless of calorie content.
  • What about total fluid consumed? The diet-soda group may have drunk more fluid overall, making them feel fuller and eat less food.

The study didn't reveal what other beverages besides water was drunk by the non-soda group. Did they drink more fruit juice or other calorie-containing beverages that contributed to their daily calories?

Bottom line:

  • Drinking water and diet soda, rather than calorie containing beverages helps with weight loss.
  • Water is still the absolute optimal choice for a zero-calorie beverage.
  • More studies need to be conducted to determine if diet sodas are truly helpful in long-term weight management.
  • Long-term effects of artificial sweeteners on overall health are unknown. Moderation or abstaining is still best!
  • My recommendations will still remain the same: Drink mostly water, followed by unsweetened tea and coffee in moderation. Drink diet soda occasionally (1x/week or less) until we know more.

Need some variety without diet soda?

Even I get tired of plain water sometimes, especially during the hot summer months. Here are some alternatives to spice it up and avoid both sodas and diet drinks altogether:

  • Add lemon, lime or orange slices to water
  • Add fresh herbs like mint or rosemary
  • Try sparkling water with fresh lemon juice
  • Mix ½ unsweetened ice tea with ½ sparkling water for a refreshing spritzer (my favorite!)
  • Drink from a water bottle with a straw