Why Do Diet Sodas Make You Fat?

Is Mixing Diet Sodas With Carbs Bad For You?

Why Do Sodas Cause Obesity?Many people, and many doctors, believe that diet sodas and artificially sweetened foods are a healthy choice. After all:

  • Cutting calories by drinking diet sodas and eating artificially sweetened foods should help you lose weight.
  • If sugar is the problem for diabetics, diet sodas and artificially sweetened foods should be a healthier choice.

On the surface, these ideas appear to be self-evident. They seem to be “no-brainers”. The truth, however, is more complicated.

When studies are tightly controlled by dietitians so that the people consuming diet sodas don’t add any extra calories to their diet, the results are exactly as expected. People consuming diet sodas lose weight compared to people drinking regular sodas.

However, as I have described in an earlier issue of “Health Tips From the Professor”, the results are different in the real world where you don’t have a dietitian looking over your shoulder. In those studies, diet sodas are just as likely to cause weight gain as regular sodas.

As Barry Popkin, a colleague at the University of North Carolina, put it” “The problem is that we [Americans] are using diet sodas to wash down our Big Macs and fries.” In short, people drinking diet sodas tend to increase their caloric intake by adding other foods to their diet. Even worse, the added foods aren’t usually fruits and vegetables. They are highly processed junk foods.

Why is that? The short answer is that nobody knows (more about that later). However, a recent study (JR Dalenberg et al, Cell Metabolism, 31: 493-502, 2020) suggests an unexpected mechanism for the weight gain associated with diet soda consumption. Let’s look at that study.

How Was The Study Done?

Clinical StudyThe study recruited 45 healthy young adults (ages 20-45) who habitually consumed less than 3 diet sodas a month. They were randomly assigned to three groups. The participants in each group came into the testing facility seven times over a span of 2 weeks. Each time they were given 12 ounces of one of three equally sweet tasting beverages in a randomized, double-blind fashion.

  • Group 1 received a sucralose-sweetened drink contained 0.06 grams of sucralose (equivalent to two packets of Splenda).
  • Group 2 received a sugar-sweetened drink contained 7 teaspoons of sucrose (table sugar).
  • Group 3 received a combo drink contained 0.06 grams of sucralose plus 7 teaspoons of maltodextrin. Maltodextrin is a water-soluble carbohydrate that does not have a sweet taste.

o   Maltodextrin was used because Splenda and most other commercial sucralose products contain it along with sucralose. You need something to fill up those little sucralose-containing packets.

o   This drink was included as a control. The expectation was that it would give the same results as the sucralose-sweetened drink.

Three measurements were performed prior to and following the 2-week testing period:

  • An oral glucose tolerance test in which participants drink a beverage containing a fixed amount of glucose. Then their blood sugar and blood insulin levels are measured over the next two hours.

o   This is a measure of how well they were able to control their blood sugar levels.

  • A test in which they were given samples that had either a sweet, sour, salty, or savory taste. Then:

o   They were asked to identify each taste and report how strong the taste was.

o   MRI scans of their brains were performed to determine how strongly their brains responded to each of the tastes.

Is Mixing Diet Soda With Carbs Bad For You?

The results were surprising. The first surprise came when the investigators unblinded the results of the oral glucose tolerance test:

  • Blood sugar and blood insulin responses were unaffected by the 2-week exposure to sugar-sweetened drinks.

o   This was expected.

  • Blood sugar and blood insulin were relatively unaffected by the 2-week exposure to sucralose-sweetened drinks. If anything, the control of blood sugar levels was slightly improved at the end of two weeks.

o   This was a disappointment for the investigators. One of the prevailing theories is that artificially sweetened beverages alter the blood sugar response. The investigators found no evidence for that idea.

  • Following the 2-week exposure to the combo drinks (sucralose plus maltodextrin), blood sugar levels were unaffected, but blood insulin levels were increased. This implies that more insulin was required to control blood sugar levels. In other words, these participants had developed insulin resistance.

o   This result was unexpected. Remember the investigators had included this drink as a control.

o   The investigators pointed out that the insulin resistance associated with the sucralose-maltodextrin combo could increase the risk of type 2 diabetes and obesity.

  • Because of this unexpected result, the investigators did a follow-up study in which participants were given a maltodextrin-only drink using the same study protocol. The oral glucose tolerance test was unchanged by the 2-week exposure to maltodextrin-only drinks.

When the investigators conducted taste tests, the ability of participants to taste all four flavors was unchanged by a 2-week exposure to any of the drinks.

However, when the investigators did MRI scans to measure the brain’s response to these flavors:

  • A two-week exposure to the sucralose plus maltodextrin drinks reduced the brain’s response to sweet but not to any of the other flavors.

o   In other words, the subjects could still taste sweet flavors, but their brains were not responding to the sweet taste. Since sweetness activates pleasure centers in the brain this could lead to an increased appetite for sweet-tasting foods.

o   This might explain the weight gain that has been observed in many previous studies of diet sodas.

  • Two-week exposures to the other drinks had no effect on the brain’s response to any of the flavors. Once again, this effect was only seen in the sucralose-maltodextrin combination.

The investigators concluded:

  • “Consumption of sucralose combined with carbohydrates impairs insulin sensitivity…and…neural responses to sugar.
  • Insulin sensitivity is not altered by sucralose or carbohydrate consumption alone.
  • The results suggest that consumption of sucralose in the presence of a carbohydrate dysregulates gut-brain regulation of glucose metabolism.”

The investigators pointed out that this could have several adverse consequences. Again, in the words of the authors:

“Similar exposure combinations (artificial sweeteners plus carbohydrates) almost certainly occur in free-living humans, especially if one considers the consumption of a diet drink along with a meal. This raises the possibility that the combination effect may be a major contributor to the rise in incidence of type 2 diabetes and obesity. If so, addition of artificial sweeteners to increase the sweetness of carbohydrate-containing food and beverages should be discouraged and consumption of diet drinks with meals should be counseled against.”

Why Do Diet Sodas Make You Fat?

As I mentioned at the start of this article, there are a lot of hypotheses as to why diet sodas make us fat. These hypotheses break down into two classifications: psychological and physiological.

The psychological hypothesis is easiest to explain. Essentially, it goes like this: We feel virtuous for choosing a zero-calorie sweetener, so we allow ourselves to eat more of our favorite foods. It is unlikely that this hypothesis holds for all diet soda drinkers. However, it is also hard to exclude it as at least part of the explanation for the food overconsumption associated with diet soda use.

There are multiple physiological hypotheses. Most of them are complicated, but here are simplified explanations of the three most popular hypotheses:

  • The sweet taste of artificial sweeteners tricks the brain into triggering insulin release by the pancreas. This causes blood sugar levels to plummet, which increases appetite.
  • The sweet taste of artificial sweeteners is not appropriately recognized by the brain. This diminishes release of hormones that suppress appetite.
  • Artificial sweeteners interfere with insulin signaling pathways, which leads to insulin resistance.

There is some evidence for and against each of these hypotheses.

However, this study introduces a new physiological hypothesis – namely that it is the combination of artificial sweeteners and carbohydrates that results in a dysregulation of the normal mechanisms controlling appetite and blood sugar.

What Does This Study Mean For You?

Diet Soda DangersLet’s start with the obvious. This is just a hypothesis.

  • This was a very small study. Until it is confirmed by other, larger studies, we don’t know whether it is true.
  • This study only tested sucralose. We don’t know whether this applies to other artificial sweeteners.
  • The study only tested maltodextrin in combination with sucralose. We don’t know whether it applies to other carbohydrates.

Therefore, in discussing how this study applies to you, let’s consider two possibilities – if it is true, and if it is false.

If this hypothesis is true, it is concerning because:

  • We often consume diet sodas with meals. If, for example, we take the earlier example of a diet soda with a Big Mac and fries, both the hamburger bun and the fries are high carbohydrate foods.

 

  • Sucralose and other artificial sweeteners are used in low calorie versions of many carbohydrate rich processed foods.

If this hypothesis is false, it does not change the underlying association of diet soda consumption with weight gain and type 2 diabetes. It is merely an attempt to explain that association. We should still try to eliminate diet sodas and reduce our consumption of artificially sweetened, low calorie foods.

My recommendation is to substitute water and other unsweetened beverages for the diet drinks or sugar sweetened beverages you are currently consuming. If you crave the fizz of sodas, drink carbonated water. If you need more taste, try herbal teas or infuse water with slices of lemon, lime, or your favorite fruit. If you buy commercial brands of flavored water, check the labels carefully. They may contain sugars or artificial sweeteners. Those you want to avoid.

The Bottom Line

Many studies have called into question the assumption that diet sodas and diet foods help us lose weight. In fact, most of these studies show that diet soda consumption is associated with weight gain rather than weight loss.

There are many hypotheses to explain this association, but none of them have been proven at present.

This study introduces a new hypothesis – namely that the combination of artificial sweeteners and carbohydrates results in a dysregulation of the normal mechanisms controlling appetite and blood sugar. In particular, this study suggested that combining sucralose with carbohydrates caused insulin resistance and reduce the ability of the brain to respond appropriately to sweet tastes.

The authors concluded: “Similar exposure combinations (artificial sweeteners plus carbohydrates) almost certainly occur in free-living humans, especially if one considers the consumption of a diet drink along with a meal. This raises the possibility that the combination effect may be a major contributor to the rise in incidence of type 2 diabetes and obesity. If so, addition of artificial sweeteners to increase the sweetness of carbohydrate-containing food and beverages should be discouraged and consumption of diet drinks with meals should be counseled against.”

If this hypothesis is true, it is concerning because:

  • We often consume diet sodas with meals. If, for example, we take the example of a diet soda with a Big Mac and fries, both the hamburger bun and the fries are high carbohydrate foods.
  • Artificial sweeteners are used in low calorie versions of many carbohydrate rich processed foods.

If this hypothesis is false, it does not change the underlying association of diet soda consumption with weight gain and type 2 diabetes. It is merely an attempt to explain that association. We should still try to eliminate diet sodas and reduce our consumption of artificially sweetened, low calorie foods.

My recommendation is to substitute water and other unsweetened beverages for the diet drinks or sugar sweetened beverages you are currently consuming. If you crave the fizz of sodas, drink carbonated water. If you need more taste, try herbal teas or infuse water with slices of lemon, lime, or your favorite fruit. If you buy commercial brands of flavored water, check the labels carefully. They may contain sugars or artificial sweeteners. Those you want to avoid.

For more details, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Do Sodas Increase Your Risk Of Dying?

Are Diet Sodas Just As Bad As Regular Sodas?

Author: Dr. Stephen Chaney

 

Americans love our sodas.

  • 48% of Americans drink 2 or more sodas every day. Even worse:
  • 61% of children and 56% of young adults consume 2 or more sodas every day.
  • The average consumption for soda drinkers is 21 ounces a day.

do sodas increase your risk of dyingHowever, the word is out that regular (sugar sweetened) sodas increase our risk of obesity, diabetes, and heart disease, so many people are switching to diet (artificially sweetened) sodas. In a recent survey looking at diet versus regular soda consumption:

  • 43% of adults chose diet sodas rather than regular sodas.

When this was broken down by gender:

  • 46% of women and 39% of men preferred diet sodas.

When this was broken down by demographics:

  • Older adults, people who aren’t white, and people making less than $30,000/year were the groups most likely to choose diet sodas.

However, recent studies have called into question our assumptions about the benefits of diet sodas. These studies suggest that people consuming diet sodas are just as likely to become obese and to develop diabetes and heart disease as those consuming regular sodas. Some studies have even suggested that diet sodas, but not regular sodas, increase our risk of stroke. I have discussed the evidence for these concerns about diet sodas in a recent issue of Health Tips From the Professor.

However, the latest study (A Mullee et al, JAMA Internal Medicine. Doi: 10.1001/jamainternalmed.2019.2478 ) ups the ante. It suggests that sodas increase our risk of dying and that diet sodas may be worse for us than regular sodas.

How Was The Study Done?

soda studyThis study utilized data from the European Prospective Investigation into Cancer and Nutrition (EPIC). In particular, this study enrolled 451,743 adults (average age = 51) from 10 countries in Europe and followed them for between 16 and 19 years. In short, this was a very large study, and it followed study participants for a long time.

Participants were excluded from the study if they had been diagnosed with cancer, heart disease, stoke, or diabetes prior to the beginning of the study.

At the beginning of the study the participants filled out a diet survey which asked, among other things, how many 8-oz glasses of regular sodas and/or diet sodas they consumed per month, week, or day.

Mortality data were obtained from each country’s health records. During the study, 41,963 deaths were recorded.

 

Do Sodas Increase Your Risk Of Dying?

 

vampire holding sodaThe results of the study were striking. When they looked at the number of deaths that occurred during the study, and compared people who consumed ≥ 2 glasses/day to those who consumed ˂ 1 glass/month, death from any cause was increased by:

  • 17% for all sodas.
  • 8% for regular sodas.
  • 26% for diet sodas.

Both total soda consumption and diet soda consumption increased the risk of death due to circulatory diseases (atherosclerosis, heart attack, congestive heart failure, and stroke). When they compared people who consumed ≥ 1 glass/day to those consuming ˂ 1 glass per month, the increase was:

  • 27% for total soda consumption
  • 52% for diet soda consumption.

Both total soda consumption and regular soda consumption increased the risk of death due to digestive diseases (diverticulitis, liver disease, and colon cancer). When they compared people who consumed ≥ 1 glass per day to those consuming ˂ 1 glass per month, the increase was:

  • 50% for total soda consumption.
  • 59% for regular soda consumption.

Total soda consumption (≥ 1 glass per day compared to ˂ 1 glass per month) also increased the risk of:

  • Colon cancer by 25%.
  • Parkinson disease by 59%.

The results were essentially the same for men and women.

The authors concluded: “This study found that consumption of total, sugar-sweetened, and artificially sweetened soft drinks was positively associated with all-cause deaths in this large European cohort; the results are supportive of public health campaigns aimed at limiting the consumption of soft drinks.”

What Are The Strengths and Weaknesses Of This Study?

strengths and weaknessesThe strengths of this study are its size (451,743 participants, 41,693 deaths) and duration (16-19 years). The size allows for conclusions that are highly statistically significant. The duration allows enough time for diseases to develop and deaths to occur.

The weakness of this study is that it is an association study. Association studies do not prove cause and effect. There is always a chance that the association is caused by some other variable that was not measured.

For example, in this study when high consumers of sodas (≥ 2 glasses/day) were compared to low consumers of sodas (˂ 1 glass/month), they were more likely to be:

  • Younger.
  • Current smokers.
  • Physically active.
  • Overweight.

You may have noticed that two of these variables (age and physical activity) decrease the risk of death while the other two (smoking and weight) increase the risk of death. However, the authors did not just assume they cancelled each other out. They statistically corrected for these variables and many others in coming to their conclusions.

Of these variables, weight is the most concerning. We know from previous studies that soda consumption is likely to lead to obesity, and obesity increases the risk of death. However, the authors of this study not only statistically corrected for obesity. They also looked at the effect of high soda consumption on death in a subgroup of participants who were at a healthy weight (BMI ˂ 25). The increased risk of death was:

  • 18% for all sodas.
  • 11% for regular sodas.
  • 27% for diet sodas.

In other words, the effect of sodas on the risk of death was virtually identical for those who were at ideal weight and those who were overweight. This finding significantly strengthens the conclusion of the study.

Finally, the conclusions of this study are strengthened by two recent, very large studies in the US that have come to similar conclusions.

All of these are association studies. However, nobody is going to do a 15-20 year randomized, placebo-controlled study in which regular and diet soda consumption are compared to water. These association studies are the best evidence we are likely to get.

 

Are Diet Sodas Just As Bad As Regular Sodas?

 

sugar free soda canThe handwriting about regular sodas has been on the wall for some time. The soda industry is still claiming that “soft drinks are safe to consume as part of a balanced diet,” but virtually all medical and public health organizations recommend that we decrease soda consumption.

But what do we replace those sodas with? Many public health organizations believe that the American public is so wedded to our sodas that diet sodas are the only viable alternative. But the evidence that diet sodas are not a good alternative to regular sodas continues to mount.

As I said in the introduction, recent studies suggest that people consuming diet sodas are just as likely to become obese and to develop diabetes and heart disease as those consuming regular sodas. Some studies have even suggested that diet sodas, but not regular sodas, increase our risk of stroke. I have discussed the evidence for these concerns about diet sodas in a recent issue of Health Tips From the Professor.

Even worse, this study and two other recent studies suggest that diet sodas are just as likely to increase the risk of premature death as regular sodas. The evidence is starting to become overwhelming that diet sodas are just as bad for us as regular sodas, and we should start turning to healthier alternatives.

Pure water is, of course, the best alternative. However, if plain water is too boring, try herbal teas. If you crave the fizz of sodas, try unsweetened sparkling water, perhaps infused with a little of your favorite fresh fruit. If you crave the caffeine of sodas, coffee or tea might suit you best, preferably without the sugar and cream. There are just two caveats:

  • Tea and coffee should not be your only source of liquid.
  • It goes without saying that you want to avoid the 500 calorie Starbucks extravaganzas.

 

The Bottom Line

 

A recent study followed 451,743 adults for 16-19 years and asked what effect soda consumption had on their risk of dying. The results of the study were striking. When they looked at the number of deaths that occurred during the study, and compared people who consumed ≥ 2 glasses/day to those who consumed ˂ 1 glass/month, death from any cause was increased by:

  • 17% for all sodas.
  • 8% for regular sodas.
  • 26% for diet sodas.

Both total soda consumption and diet soda consumption increased the risk of death due to circulatory diseases (atherosclerosis, heart attack, congestive heart failure, and stroke). When they compared people who consumed ≥ 1 glass/day to those consuming ˂ 1 glass per month, the increase was:

  • 27% for total soda consumption
  • 52% for diet soda consumption.

The authors of the study concluded: “This study found that consumption of total, sugar-sweetened, and artificially sweetened soft drinks was positively associated with all-cause deaths in this large European cohort; the results are supportive of public health campaigns aimed at limiting the consumption of soft drinks.”

The evidence is starting to become overwhelming that diet sodas are just as bad for us as regular sodas, and we should start turning to healthier alternatives.

Pure water is, of course, the best alternative. However, if plain water is too boring, try herbal teas. If you crave the fizz of sodas, try unsweetened sparkling water, perhaps infused with a little of your favorite fresh fruit. If you crave the caffeine of sodas, coffee or tea might suit you best, preferably without the sugar and cream. There are just two caveats:

  • Tea and coffee should not be your only source of liquid.
  • It goes without saying that you want to avoid the 500 calorie Starbucks extravaganzas.

For more details on the study and what it means for you, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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