A regular 12-ounce bottle of Mountain Dew soda contains 46 grams of added sugar (almost 4 tablespoons), while a diet soda contains zero grams of sugar and zero calories. So, it seems obvious that the diet Dew is the healthier choice—0 calories and sugar grams versus 46 sugar grams and 170 calories? It’s lemons versus limes.
But when you ask the question “what happens to my body when I drink that diet soda,” the answer isn’t so straightforward. So, let’s pick through the pros and cons.
Drinking diet soda instead of regular versions is linked to a reduction in body weight, body mass index, and percentage of body fat, especially among the obese, according to data published in JAMA Network Open. Another study in the journal Obesity found that people who drank 24 ounces of diet soda daily for a year maintained a weight loss of up to 16 pounds.
A systematic review and meta-analysis in 2017 linked both sugar-sweetened and artificially sweetened beverages to weight gain. Other data suggest that non-nutritive sweeteners may stimulate appetite, leading to weight gain over time. “But much of the data is observational in nature,” says Eatthis.com medical board member and registered dietitian nutritionist Lauren Manaker, MS, RDN, LDN. “Therefore, more studies are needed before we make a definitive connection.”
“Artificial sweeteners are digested differently than natural sugar,” explains Justine Rosado, RDN, a registered dietitian nutritionist and certified diabetes care and education specialist with The Nutrition Queens. “What determines their metabolic fate is their complex composition, with some completely bypassing the typical absorption and digestion phases that calorie-containing foods undergo.”
The bottom line is that the research is inconclusive. “Most studies show that artificial sweeteners have varying impacts on weight control, though in large part they do not cause individuals to lose or gain weight,” Rosado says.
Artificial sweeteners like aspartame (Equal), Saccharin (Sweet’N Lo), and Sucralose (Splenda) take some getting used to. Some nonnutritive sweeteners can be 180 to 13,000 times sweeter than sugar and may change taste preferences over time, according to research in The Permanente Journal.
“Unlike drinking regular soda that is loaded with added sugars, diet soda consumption shouldn’t cause a blood sugar spike,” says Manaker. People who have diabetes but like soda may find diet soda to be a good option. “Used in appropriate amounts, diet sodas are a safe way to enjoy a sweet-tasting beverage while keeping blood sugars stable,” says Rosado.
“Soft drink consumption, regardless of whether it is diet or sugar-sweetened, may have adverse effects on bone mineral density,” says Manaker, author of The First Time Mom’s Pregnancy Cookbook. “But the studies show mixed results; dark sodas, in particular, seem to pose the most risk.” Excessive intake of phosphoric acid in sodas creates imbalances in mineral ratios that are linked to osteoporosis and fractures, according to a 2020 report in Nutrients.
“Many diet sodas contain caffeine, which can give people a boost when they are feeling sluggish,” says Manaker. “Unfortunately, if you drink these caffeinated sodas late in the day, you may have trouble sleeping thanks to the stimulation.”
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