It's such a common line: "once you stop eating so much sugar, your taste buds will adjust." But what does that actually mean? How do taste buds "adjust?" How long does it take?
From the research that we have, it does seem like this is a real thing that actually happens, even though it takes a few weeks for the magic to really start happening. But the “why” is even more interesting: it’s not just about the taste buds in your mouth. Taste receptors in the gut also get involved, and the process of “adjusting” to less sugar is a whole-body affair.
“Adjustment” Does Happen, but it Takes a Few Weeks.
In this study, researchers gave subjects one of two different diets for five months.
- Group 1: ate their usual diet for 1 month, a low-sugar diet for 3 months, and then a self-selected diet for 1 month.
- Group 2: ate their usual diet for 4 months, and then a self-selected diet for 1 month.
The low-sugar diet was designed to reduce calories from sugar by 40% (replacing them with protein, fat, and complex carbs). The participants weren't allowed to replace sugar with artificial sweeteners. They were also instructed not to try to lose weight: the participants who cut sugar had to replace those calories with other calories.
During the three months of the intervention, the low-sugar group actually exceeded their target sugar reduction. During the fifth month, when they got to choose their own diet again, they ate more sugar, but still about 20% less sugar than they had eaten at the beginning of the study.
The main finding from this study was that it took a month of reduced sugar intake for any "adjustment" to occur. The low-sugar group didn't taste anything differently until the second month of the intervention diet. Starting in the second month of sugar reduction, the reduced-sugar group tasted sweetness more intensely, so the same amount of sugar tasted sweeter to them. In the fourth overall month (the third month of the low-sugar intervention), they tasted sweetness even more intensely. The differences went away during the final month, when both groups got to choose their own diet.
Admittedly, this study was based on self-reported food intake, and self-reported food intake is notoriously bad. It's not even that people intentionally lie; they just forget what they ate, especially if it was a snack or "just a bite." But if anything, you'd expect people in the low-sugar group to underestimate and say they were eating less sugar than they actually were. So even if the records are unreliable, this study just showed that even a very small decrease in sugar intake could affect taste.
Of course, this was the average. Individual people might find that the effects start much faster for them personally. But if it doesn't kick in for a few weeks, don't worry: that's normal.
It's Not Just the "Taste Buds" Adjusting
So why does that adjustment happen?
Saying that your "taste buds" adjust is an easy shorthand, but the adjustment is actually much bigger than the taste receptors on your tongue or even in your mouth. Your gut also has taste receptors (for fats as well as sugars, but here we're focusing on sugar). The sweet taste receptors in the gut can influence the release of hormones that control blood sugar, hunger, and appetite.
An interesting piece of evidence for this is what happens to people after weight-loss surgery. Roux-en-Y gastric bypass surgery increases sensitivity to very sweet tastes, even though bariatric surgery obviously doesn't directly affect the taste buds. But what it does affect is the gut. The alterations to gut hormones caused by bariatric surgery might affect taste receptors in the gut, causing a higher sensitivity to sweetness (so the same amount of sugar tastes "sweeter").
Another important hormonal connection is leptin. Leptin is a hormone that helps regulate appetite. According to the study above, leptin makes people makes people less sensitive to sweet tastes. People with obesity have very high levels of leptin, which could make them less sensitive to sweetness (so they have to eat more sugar to get that “sweet” taste, which contributes to their obesity). Just losing weight (and lowering leptin levels) might be enough to increase sensitivity to sweetness.
There’s also a genetic component to how “sweet” something tastes to you, but new research has found that the genetic sensitivity to sweetness might also be modified by BMI.
A low-sugar diet might affect preference for sweet taste by working on those taste receptors as well as on the ones in your mouth. Alternately, it could work by affecting the gut flora. Whatever species of gut flora you feed, those are the ones you'll get more of. Then you have even more gut flora, all demanding more of whatever you ate that they liked in the first place. Eating more simple sugars would encourage the growth of gut flora that eat simple sugars; eating fewer simple sugars could reduce the “taste” for sugar by encouraging gut flora that want other types of food.
In other words, it's not just the taste buds in your mouth "getting used to" a lower baseline level of stimulation. It's a whole range of things all over your body. Losing excess body fat and healing any gut damage could help reduce a person's taste for sugar completely independently of their diet - but of course, those things tend to happen on a low-sugar diet anyway.
Sweetness vs. Pleasantness
In the first study, all subjects gave foods roughly the same level of pleasantness, even though the low-sugar group perceived them as sweeter. The same was true for patients after Roux-en-Y surgery: even though they rated a sweet drink as more intensely sweet post-surgery, patients still liked the taste just as much.
Explaining that would get into food reward and the brain response to glucose, but it's worth noting if only because it might explain why some people still crave very sugary treats even after being on Paleo for a while. It tastes sweeter, but it doesn’t necessarily taste worse.
Summing it Up
Taste for sweetness depends on all kinds of things. There's evidence that some of it is conditioned by a person's normal diet: the more sugar they usually eat, the more they need for something to taste sweet. But there are also sweet taste receptors in the gut, and there's evidence that hormone levels and the composition of the gut flora influence how much sweetness we perceive and want. And then, of course, there's genetics: some people are genetically more or less sensitive to sweeteners, and that genetic sensitivity might be modified by BMI
Overall though, the evidence does suggest that if you eat less sugar, you really do “get used to it” after a few weeks, and less-sweet foods start tasting “sweeter.”