Replacing sugar with sweeteners can actually help you lose weight

For years, low-calorie sweeteners have existed in a kind of nutritional limbo. They were marketed as tools for weight control, criticized for possible side effects, and difficult to evaluate because most studies were short or conducted under artificial conditions.

A new, unusually long trial takes a more realistic approach and delivers a clear takeaway.

When people swap sugar for low-calorie sweeteners within an otherwise healthy diet, they tend to maintain their weight – or even lose weight. Moreover, their gut microbes shift in a direction that could support that success.

Two-phase diet experiment

The study, led by Ellen Blaak at Maastricht University, started with a reset. Researchers enrolled 341 higher weight adults or those with obesity across several European countries. They then put everyone on a tightly controlled low-calorie diet for two months.

The goal was simple and blunt: lose a meaningful amount of weight. On average, participants dropped about 22 pounds (10 kilograms) – enough to make the maintenance phase matter.

Then came the harder part. For the next 10 months, everyone followed a healthy eating pattern capped at less than 10 percent of calories from sugar.

Half the group was told to avoid low-calorie sweeteners entirely. The other half was encouraged to reach for sweetener-based versions when a sugary food or drink would have been the default.

This wasn’t a single-ingredient trial; participants used at least 16 different sweeteners, mixed and matched the way real consumers do.

Sweeteners help sustain weight loss

After those 10 months, the differences weren’t dramatic, but they were steady. The sweetener group maintained about 3.5 pounds (1.6 kilograms) more of their initial weight loss than the group avoiding sweeteners.

In the world of weight maintenance – where small, steady regains are the norm – that’s a meaningful gap. Keeping even a couple of kilos off over the long haul translates into lower risk for diabetes, joint pain, and heart disease.

Blaak’s bottom line is restrained but firm: replacing sugar with low-calorie sweeteners, within a healthy diet, may help you in maintaining body weight. It’s not a miracle; it’s an assist. And for maintenance, assists are gold.

Sweeteners shift gut balance

The researchers didn’t stop at the scale. Stool samples suggested that those using sweeteners had a higher abundance of bacteria that produce short-chain fatty acids (SCFAs).

These metabolites were linked in past research to better blood sugar control, lower inflammation, and improved satiety.

That doesn’t prove cause and effect, and it doesn’t mean every sweetener is equal. But it hints that the gut environment may be moving in a direction that helps people hold the line after weight loss.

Microbiome scientists will rightly ask hard questions here. Are the changes driven by the sweeteners, by the weight loss, by the overall diet, or by all three? The honest answer is “all three, to varying degrees.”

Still, the direction of travel – toward SCFA-producers – is consistent with better metabolic resilience.

Cutting through sweetener confusion

A lot of the scary headlines about sweeteners come from short trials, single-sweetener tests, or studies where sweeteners are added on top of an already sugary diet.

This work did two things differently. It ran long enough to see what sticks after the honeymoon period, and it framed sweeteners as substitutes for sugar within a structured, lower-sugar diet.

That “instead of, not in addition to” framing matters. Replacing sugar calories without triggering rebound overeating is exactly how you preserve a calorie gap months after the initial diet ends.

What the study doesn’t prove

This isn’t a free pass for every packet and can on the shelf. The study wasn’t built to compare specific sweeteners or to track long-term cardiovascular outcomes.

It can’t reveal which brand is best or whether one sweetener interacts more favorably with the microbiome than another.

And the maintenance edge – while real – was modest. If sweetened alternatives lead you to rely more on ultra-processed foods, you can erase the benefit quickly.

Sweetener swaps that work

If you’ve lost weight and want to keep it off, start by swapping sugary staples – soda, flavored yogurts, sweetened coffees, and desserts – for low-calorie sweetener versions.

This approach works best when the rest of your diet is built on fiber-rich plants, lean proteins, and minimally processed foods.

Think substitution, not addition. Let sweeteners replace sugar where you notice it most, and let whole foods do the heavy lifting on fullness and nutrition.

Maintaining weight loss is a challenge

For clinicians and policymakers, the message is nuanced. Blanket warnings against sweeteners may push people back toward sugar or set them up for weight regain.

A clearer guideline is to limit added sugars, use low-calorie sweeteners when they make it easier to stick with your plan, and combine that approach with habits that promote fullness and overall metabolic health.

This long, pragmatic trial won’t end the sweetener wars, but it does shift the conversation. In the context of a healthy diet, using low-calorie sweeteners helped participants maintain more of their hard-won weight loss.

It’s not a silver bullet. It is a practical tool – one that, used wisely, can make the toughest phase of weight management a little more manageable.

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