Neither is proven to produce more weight loss than the other. Plain, unsweetened sparkling water is a low-calorie drink; diet soda may help if it replaces sugary soda and reduces beverage calories. The practical choice depends on the specific drink, what it replaces and whether it helps you sustain an overall calorie reduction.
What matters most: what the drink replaces
A drink does not cause weight loss simply because it is fizzy or sugar-free. Its likely value depends on whether it helps reduce calories overall. Replacing a sugar-sweetened drink with water or a low- or no-calorie alternative can lower beverage calories; adding a diet drink without changing what you otherwise consume may not.
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For context, the CDC says a 12-ounce regular soda has about 42 grams of added sugar and 150 calories. Those figures describe regular soda, not every sweetened drink or serving size. CDC: sugary drinks
How the two options compare
| Choice | Weight-loss relevance | What to check |
|---|---|---|
| Plain, unsweetened sparkling water | Low-calorie option that can replace sugary drinks; no cited evidence establishes greater weight loss than diet soda. | Confirm it is unsweetened and check the nutrition facts, especially for flavored products. CDC: water and healthier drinks |
| Diet soda or another low-/no-calorie sweetened drink | May reduce beverage calories when it replaces a sugar-sweetened drink. Evidence does not establish a long-term weight-loss advantage over water. | Read the ingredients and nutrition label; products and sweeteners vary. CDC: low-calorie sweeteners |
What the evidence says about diet soda
Substitution can help; the effect is not a special property of diet soda
A 2022 systematic review and meta-analysis in JAMA Network Open included 17 randomized trials. It found that low- and no-calorie sweetened beverages used instead of sugar-sweetened beverages were associated with reductions in body weight and related measures, with benefits similar in direction to water over the moderate term. The authors’ interpretation concerned adults with overweight or obesity who were at risk for or had diabetes; it does not prove a universal or long-term benefit. JAMA Network Open, 2022
#1 Best Overall
- FRESH FIZZ ON DEMAND: This SodaStream TERRA CO2 bundle is perfect for Seltzer lovers; It contains 3 ready-to-use CO2 cylinders that together make 180 liters (48 gallons) of fresh sparkling water in seconds, right on your countertop.
- A SECURE SNAP AND SEAL: The Quick Connect CO2 cylinder clicks in with one push, and the bottle snaps into place before you fizz. The seal is built to keep the bubbles in the bottle and the water off your counter, so even your first drink feels easy.
- THE QUICK CONNECT CO2 SYSTEM: Each 60L Quick Connect cylinder makes up to 60 liters (16 gallons) of sparkling water. When it runs low, return, refill, and reuse it through SodaStream CO2 cylinder exchange at participating retailers. The Quick Connect fit makes every swap simple, so you are back to fizzing fast.
- BUILT FOR DAILY USE: The reusable bottles are BPA free and dishwasher safe, ready for the next round whenever you are. The slim machine sits neatly on the counter and tucks under most upper cabinets, built to keep up with you day after day.
- ONE MACHINE, EVERY KIND OF DRINK: After fizzing your water, add flavor drops for zero sugar sparkling water, stir in Pepsi or Mountain Dew syrups for a classic soda, or add a squeeze of citrus for a fresh twist. One soda maker, every kind of drink, made by you.
In its diabetes-care guidance, the American Diabetes Association describes mixed evidence across reviews. It notes small improvements in weight and cardiometabolic risk factors when low- or no-calorie sweetened drinks are used in place of sugar-sweetened drinks, in a direction similar to water. It also cautions that these sweeteners do not produce weight-loss benefits without energy restriction, and that eating or drinking more elsewhere can offset saved calories. ADA Standards of Care in Diabetes—2025
Long-term conclusions and guidance differ
The World Health Organization’s 2022 systematic review found that short-term randomized trials generally suggested lower body weight when non-sugar sweeteners were used alongside energy restriction, but found no clear consensus on long-term weight loss or maintenance. In 2023, WHO recommended against using non-sugar sweeteners as a strategy to control body weight or reduce noncommunicable disease risk. That is a weight-control recommendation, not a toxicological assessment or proof that approved diet drinks are unsafe. WHO: systematic review, 2022 · WHO: guideline, 2023
Rank #2
- 🍹 Elevate your hydration game with the SodaStream ART Sparkling Water Maker Starter Pack; transform ordinary tap water into refreshing sparkling water with a simple pull of a lever; ideal for creating fizzy beverages for family gatherings or solo refreshment moments. This kit contains 1x 32 Fl Oz Slim Carbonating Bottle and 1x 16 Fl Oz On-The-Go My Only Bottle with a carrying strap, making it easy to take your bubbles with you for any occasion
- 🖤 Discover the sleek elegance of the SodaStream ART in Black; its stylish design with retro metal accents complements any kitchen décor; a perfect blend of form and function for modern living
- 🌿 Enjoy eco-friendly carbonation with the SodaStream ART; powered by reusable CO2 cylinders, each cylinder carbonates up to 16 gallons of water, the equivalent of 120 plastic bottles; reduce your carbon footprint while enjoying endless sparkling drinks at home
- 🎨 Unleash your creativity with the SodaStream ART, compatible with SodaStream, Pepsi, Bubly and Mountain Dew flavors, and many more! | Mix and match to create your own signature drinks, whether you prefer classic sparkling water or unique flavored concoctions
- 🥤 Experience the convenience of the SodaStream ART with its easy-to-use snap-lock bottle insertion; quickly carbonate your water with minimal effort, making it suitable for busy mornings or spontaneous gatherings with friends
The ADA also notes that observational links between sweetener use and weight gain do not establish cause and effect: people may switch to diet drinks because they already have weight concerns, and other differences between groups may influence the association.
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- If you usually drink regular soda: replacing it with plain sparkling water or a diet soda may reduce beverage calories. Choose the option you can stick with, and consider whether it leads you to compensate by eating or drinking more elsewhere.
- If you prefer unsweetened drinks: plain sparkling water offers fizz without the calories of sugar-sweetened soda. Check labels rather than assuming every flavored or sparkling product is unsweetened.
- If you prefer a sweet taste: diet soda can be a practical replacement for sugary soda, but it is not a weight-loss treatment and is not established as better than water for weight loss.
The CDC lists sparkling water and seltzers among low-calorie choices and recommends water, including sparkling water, as a replacement for sugary drinks. Its figures for US adults—49% drank a sugar-sweetened beverage on a given day and an average of 145 calories came from those beverages—refer to 2011–2014 data, not current consumption. CDC National Center for Health Statistics, data brief 270
Rank #3
- Multi award winning design - Mysoda Ruby 2 silent water carbonator is the proud winner of The Chicago Athenaeum Green Good Design 2023, The Red Dot Award 2023 and has received the Design from Finland mark. Level up your kitchen decor with a Nordic design soda maker.
- Improved anti freeze nozzle creates a larger amount of smaller bubbles for smoother carbonation, while the scratch proof coating allows easier maintenance and a clean, premium finish. The Ruby 2 carbonation machine works perfectly as a home soda fountain machine and seltzer water maker, and is available in stunning tone to tone color schemes so you can choose the one that fits your kitchen best.
- Package includes 1x Ruby 2 sparkling water machine and 1L water bottle. Cylinder is sold separately. It uses the most common carbon cylinder for soda water makers with screw-in system, so that you can exchange your empty cylinder at your nearest store.
- Save your hard-earned cash with with an eco-friendly carbonated water maker and never ran out of soda again. Americans drink an average of 45 gallons of soda yearly, burdening both their wallets and the planet. Switch to a smarter future with Ruby 2 carbonated water maker.
- This Soda Streaming Machine is Silent and easy to use with a quick-lock mechanism and noise cancellation feature with no electricity required. Simply fill the bottle with water, attach it to the soda maker with quick-lock system, press the carbonation button 2-3 times and that's it.
Bottom line for weight loss
There is no established winner between diet soda and plain sparkling water. Choose based on the calories and ingredients in the product and, above all, whether it replaces a sugary drink and supports a sustainable reduction in overall calories. Neither drink independently causes weight loss.
Quick Recap
Best Value
- FRESH FIZZ ON DEMAND: The SodaStream TERRA turns plain tap water into fresh sparkling water in seconds, right on your countertop. One slow press gives a light fizz, a few more build a stronger bubble. This carbonated water machine puts every glass exactly where you like it, made by you, every time.
- A SECURE SNAP AND SEAL: The Quick Connect CO2 cylinder clicks in with one push, and the bottle snaps into place before you fizz. The seal is built to keep the bubbles in the bottle and the water off your counter, so even your first drink feels easy.
- THE QUICK CONNECT CO2 SYSTEM: Each 60L Quick Connect cylinder makes up to 60 liters (16 gallons) of sparkling water. When it runs low, return, refill, and reuse it through SodaStream CO2 cylinder exchange at participating retailers. The Quick Connect fit makes every swap simple, so you are back to fizzing fast.
- BUILT FOR DAILY USE: The reusable bottles are BPA free and dishwasher safe, ready for the next round whenever you are. The slim machine sits neatly on the counter and tucks under most upper cabinets, built to keep up with you day after day.
- ONE MACHINE, EVERY KIND OF DRINK: After fizzing your water, add flavor drops for zero sugar sparkling water, stir in Pepsi or Mountain Dew syrups for a classic soda, or add a squeeze of citrus for a fresh twist. One soda maker, every kind of drink, made by you.
Rank #4
- FRESH FIZZ ON DEMAND: The SodaStream TERRA turns plain tap water into fresh sparkling water in seconds, right on your countertop. One slow press gives a light fizz, a few more build a stronger bubble. This carbonated water machine puts every glass exactly where you like it, made by you, every time.
- A SECURE SNAP AND SEAL: The Quick Connect CO2 cylinder clicks in with one push, and the bottle snaps into place before you fizz. The seal is built to keep the bubbles in the bottle and the water off your counter, so even your first drink feels easy.
- THE QUICK CONNECT CO2 SYSTEM: Each 60L Quick Connect cylinder makes up to 60 liters (16 gallons) of sparkling water. When it runs low, return, refill, and reuse it through SodaStream CO2 cylinder exchange at participating retailers. The Quick Connect fit makes every swap simple, so you are back to fizzing fast.
- BUILT FOR DAILY USE: The reusable bottles are BPA free and dishwasher safe, ready for the next round whenever you are. The slim machine sits neatly on the counter and tucks under most upper cabinets, built to keep up with you day after day.
- ONE MACHINE, EVERY KIND OF DRINK: After fizzing your water, add flavor drops for zero sugar sparkling water, stir in Pepsi or Mountain Dew syrups for a classic soda, or add a squeeze of citrus for a fresh twist. One soda maker, every kind of drink, made by you.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
