It's a lot of soda to consume in one day, and — were it regular soda — most research suggests the potential consequences would be alarming. A 12-ounce can of regular Coke has 140 calories and 39 grams of sugar. By instead drinking Diet Coke, which has no calories or sugar, Trump has avoided consuming 1,680 calories and 468 grams of sugar daily.
But the effects of drinking diet soda have been long debated by experts, with some studies raising concerns about long-term health consequences. Experimental research on artificial sweeteners, like the ones found in diet soda, is inconclusive. The Canadian Medical Association Journal found in July that there are very few randomly controlled studies on artificial sweeteners — just seven trials involving only about 1,000 people — that looked at what happened when people consumed artificial sweeteners for more than six months.
Nearly half of adults and a quarter of children consume artificial sweeteners each day, according to the Journal of the Academy of Nutrition and Dietetics.
Diet soda might be a good short-term substitute for people trying to stay away from the high-sugar content of regular soda, when consumed in small amounts. Some dietitians and nutrition scientists believe sucralose and stevia, which can both be found in diet sodas, are a healthier alternative for people to enjoy sweet drinks without the calories.
But others say artificial sweeteners can confuse the brain and the body, desensitizing consumers to sugar and leading them to consume more sweets without being aware of their calorie intake.
There is one thing, however, most studies agree on: Even if diet soda is healthier, you probably shouldn't be drinking 12 cans a day.
Here's what the risks might be if — like Trump — you do.
Stroke or dementia
People who drank diet soda daily were three times more likely to develop stroke and dementia than those who consumed it weekly or less, according to a study published in April in the journal Stroke.
The study followed 2,888 people aged 45 and over for risk of stroke and 1,484 people 60 and over for dementia over 10 years. They were participants of the Framingham Heart Study, in which several thousand men and women have taken regular health tests since the 1970s.
The study found those who consumed at least one artificially sweetened drink a day, compared to less than one a week, were three times as likely to have an ischemic stroke from blood vessel blockage. They were also three times as likely to be diagnosed with dementia due to Alzheimer's disease. The effect of diet sodas persisted even if the researchers controlled for factors such as diabetes or high blood pressure.
But Matthew Pase, a Boston University School of Medicine neurologist and the study's lead author, emphasized that the research showed only a correlation — and not causation. While the risk of stroke and dementia was greater, the numbers were low.
“Three percent of the people had a new stroke and five percent developed dementia, so we're still talking about a small number of people developing either stroke or dementia,” he said in a video explaining the study.
In responding to the study, the American Beverage Association said in a statement that low-calorie sweeteners have been proven safe by worldwide government safety authorities as well as “hundreds of scientific studies.”
“There is nothing in this research that counters this well-established fact,” officials said.
An unsafe amount of caffeine consumption
About 400 milligrams of caffeine a day is what's considered safe for most healthy adults, according to the Mayo Clinic.
That amount is equal to four cups of brewed coffee and 10 cans of soda — two cans less than the amount Trump drinks.
That much caffeine can lead to migraines, insomnia, restlessness and muscle tremors.
Obesity rates have leveled off in the last decade in terms of BMI, while the consumption of noncaloric sweeteners increased.
Those patterns could mean that artificial sweeteners have helped curb obesity, but studies in recent years suggest those sweeteners are causing the exact thing the people consuming them are hoping to avoid: weight gain.
The Canadian Medical Association Journal study in July found there wasn't much evidence proving sweeteners prevented weight loss. Researchers looked at 30 studies tracking people's diets over time and found that those who consumed sweeteners were more likely to have increases in their waist and waistlines — and had a higher risk of obesity, hypertension, metabolic syndrome, Type 2 diabetes and strokes.
“I think originally it was calories were the problem, and we’ve made something that was zero calories, so we're good,” Meghan Azad, a researcher at the University of Manitoba, told The Washington Post in July. “But we’re learning that it’s not just about the calories.”
In 2015, researchers at the University of Texas Health Science Center in San Antonio examined data for nearly 10 years from 749 Mexican Americans and European Americans ages 65 and older and found that daily and occasional diet soda drinkers gained almost three times as much belly fat as non-drinkers.
Occasional diet soda drinkers added an average of 1.83 inches to their waist circumferences, while the non-drinkers added .8 inches over the nearly 10-year period. Those who consumed diet soda daily gained 3.16 inches.
But some reports show that the benefits or harm of artificial sweeteners depend on what they're paired with.
For example, 2012 study by The New England Journal of Medicine found that Dutch children who consumed one artificially sweetened beverage each day for 18 months gained less weight than those who drank one sugary beverage a day.
Then, in August, Dana Small, a neuroscientist at Yale University, told Vox that her research suggests artificial sweeteners could cause weight gain if consumed with carbohydrates, because the blend of foods disrupts the body's metabolic response. A diet drink consumed on an empty stomach could be less harmful than one consumed with, say, a Big Mac.
It's a concerning discovery, she said, because food companies are designing “healthier” products that contain blends of sweeteners and carbohydrates. For example, Chobani's Simply 100 yogurt contains 14 grams of carbohydrate (six of them from sugar) and stevia leaf extract, Vox reported.
People who drink three or more artificially sweetened beverages a day, Small told Vox, could be more likely to drink them during meals with carbs that disrupt the body's metabolic response.
In various Q & As during his campaign, Trump expressed his love for pasta, second helpings of potatoes au gratin and steak.
If he's drinking 12 cans of Diet Coke a day, it's likely he's drinking some of them with carbs.
I have never seen a thin person drinking Diet Coke.— Donald J. Trump (@realDonaldTrump) October 14, 2012
People are going crazy with my comments on Diet Coke (soda). Let's face it--this stuff just doesn't work. It makes you hungry.— Donald J. Trump (@realDonaldTrump) October 22, 2012