Wide-ranging review links artificial sweeteners with weight gain

There are many aspects of conventional dietary ideology that I don’t agree with. Not because I look for conflict and disagreement, but because so many concepts within dietary ‘conventional wisdom’ are simply not supported by the evidence (and, in fact, may be harmful).

One common theme we see crop up in dietary dogma centres around calories, and the need to reduce calorie intake if we want to lose weight. Fat is obviously in the firing line here again, and so maybe sugar. Outside the soft drinks industry, there is quite a lot of support for the idea that sugary soft drinks, say, are not good for those seeking to maintain a healthy weight. The conventional line is that artificially sweetened diet drinks are better. Even soft drink manufacturers such as the Coca Cola Company draw our attention to their artificially-sweetened offering for those concerned about weight.

However, the promotion of artificially sweetened drinks for weight control is not something I can support in good conscience. Leaving the potentially toxic nature of artificial sweeteners aside, there evidence linking artificial sweeteners and weight gain and also other issues including metabolic syndrome (‘abdominal obesity’ and raised markers for cardiovascular disease and type 2 diabetes) and type 2 diabetes.

The major findings from the scientific literature and their implications were discussed recently in a review paper in the journal Trends in Endocrinology and Metabolism, authored by behavioural neuroscientists Professor Susan Swithers from Purdue University in the US [1]. Professor Swithers has a special interest in the role of artificial sweeteners in health, and has previously published several papers on the subject.

In the review, Professor Swithers cites a recent study in which sugar-sweetened beverages were at east partially replaced with artificially sweetened ones (or water) [2]. These substitutions did improve certain health markers including waist circumference, but no more so than ‘attentional control’ (essentially, being conscious of the dietary choices we make). Also, those practising attentional control or replacing sugary drinks with water saw an improvement in fasting blood sugar levels, while those drinking artificially sweetened drinks did not. I wrote about this study here. 

Professor Swithers cites another study, this one in children, which found that drinking one artificially sweetened drink a day compared to one sugar-sweetened drink each day led to weight being 1 kg lower after 6 months, as well as lower levels of body fatness [3]. However, this study did not test how artificially sweetened drinks fared against water. Professor Swithers points our attention to a review that concludes that the evidence in children is ‘mixed’ [4].

Also, in her review, Professor Swithers cites many studies that link the drinking of artificially sweetened drinks to increased risk of, among other things, obesity, metabolic syndrome and type 2 diabetes in humans. Now, a potential explanation here, as she points out, is that individuals seeking to control their weight may be more likely to choose artificially sweetened drinks rather than sugary ones. In other words, whatever weight issue exists is ‘causing’ the increased intake of artificially sweetened drinks, rather than the other way round.

However, she also cites evidence that shows that when people are followed over time, in individuals who essentially start off at the same weight, those opting for artificially sweetened drinks are at increased risk of weight gain compared to those who, say, do not opt for these beverages. The same is true for type 2 diabetes.

These findings suggest that the idea that heavier people are more likely to opt for artificially sweetened drinks does not adequately explain the associations between these drinks and obesity and type 2 diabetes. This does throw up the possibility that artificial sweeteners have the potential to actually cause obesity and other chronic health issues. It should perhaps be borne in mind that none of the epidemiological studies where people were followed over time found artificially sweetened beverages to be associated with improved health outcomes.

Professor Swithers goes on to describe mechanisms which might explain any ability artificial sweeteners have to drive obesity and other health issues. She writes about how when we eat something with, say, sugar in it, the body responds in a way which is geared to metabolising whatever it is we’ve eaten, and that calories should be registered appropriately by the body through signals that adjust hunger to ensure we do not overeat. However, as Professor Swithers points out, there is evidence in animals that the consumption of artificially sweetened drinks disrupt these mechanisms, which in turn may lead to weight gain and other problems.

In one study, rats were fed with either saccharin or sugar-sweetened yoghurt in conjunction with their normal diet [5]. Compared to those eating sugar-sweetened yoghurt, the rats eating saccharin-laced yoghurt consumed more calories and got fatter too. The authors of this study (one of whom is Professor Swithers) concluded that:

…using artificial sweeteners in rats resulted in increased caloric intake, increased body weight, and increased adiposity [fatness].

The authors also added that:

These results suggest that consumption of products containing artificial sweeteners may lead to increased body weight and obesity by interfering with fundamental homeostatic, physiological processes.

In other study, this one from earlier this year, rats were split into three groups, each of which was given unlimited amounts of standard rat food (chow) and water [6]. The groups were also given access to yoghurt sweetened with either saccharin, aspartame or sugar (sucrose).

Rats eating the artificially sweetened yoghurt ate more chow than those eating the sugar-sweetened yoghurt. In the end, overall calorie intakes were the same. This suggests that when reduced-calorie foodstuffs are consumed, there can be a natural drive to seek those ‘missing’ calories elsewhere.

What was also interesting about this study, though, was that the rats consuming artificial sweetener gained weight at a rate faster than those eating the sugar. But the calorie intakes were essentially the same, meaning that change in weight could not be explained by differences in food intake.

Interestingly, it was noted in the previous study [5] that rats experienced some boost in their temperature after eating sugar-sweetened food that was not present after eating saccharin-sweetened food. This suggests that consuming calories from sugar boosts the metabolism in a way that artificial sweeteners may not.

Professor Swithers’ review paper is balanced and evidence-based, and concludes (quite rightly, I think) that we should be cautious over the use of sweeteners, including those that don’t contain calories.

Shortly after this study was published, someone sent me a link to an article in the Daily Mail (a tabloid newspaper in the UK) regarding the safety of artificial sweeteners here. The article, entitled ‘Sweeteners are not bad for you: Take the scare stories about diet drinks and sweets with a pinch of salt, experts say’, focuses on Professor Swithers’ review, and includes these quotes from Catherine Collins, chief dietician at St Georges Hospital in London, UK.

Sweeteners have either zero calories or are very low in calories that aren’t absorbed anyway, so are effectively zero calorie.

So the suggestion that these products are no better at preventing weight gain or diabetes, or that they in fact cause them, is unfounded, as the accepted scientific evidence demonstrates.

However, I’m not as happy as Catherine Collins to dismiss Professor Swithers’ review, particularly if this involves quoting calorie-based based dogma and ‘accepted scientific evidence’ that is not specified. Of course, it’s easy for our quotes and the science to not be represented fully in a newspaper article.

We should give Catherine Collins the benefit of the doubt, I think. It might be that she is aware of a great body of research which effectively dismantles Professor Swithers’ cogent and wide-ranging review, and provides good evidence (say, from randomised controlled trials) that artificial sweeteners are, indeed, effective aids to weight control. If she has this evidence, then no doubt she will provide it here or elsewhere.


1. Swithers SE. Artificial sweeteners produce the counterintuitive effect of inducing metabolic derangements. Trends Endocrinol Metab. 2013 Jul 3 [Epub ahead of print]

2. Tate DF, et al. Replacing caloric beverages with water or diet beverages for weight loss in adults: main results of the Choose Healthy Options Consciously Everyday (CHOICE) randomized clinical trial. Am J Clin Nutr. 2012;95(3):555-63

3. de Ruyter JC, et al. A trial of sugar-free or sugar-sweetened beverages and body weight in children. N Engl J Med. 2012;367(15):1397-406

4. Fowler SP, et al. Fueling the obesity epidemic? Artificially sweetened beverage use and long-term weight gain. Obesity (Silver Spring). 2008;16(8):1894-900

5. Swithers SE, et al. A role for sweet taste: Calorie predictive relations in energy regulation by rats. Behavioral Neuroscience. 2008;122(1):161-173

6.    Feijó Fde M, et al. Saccharin and aspartame, compared with sucrose, induce greater weight gain in adult Wistar rats, at similar total caloric intake levels. Appetite 2013;60(1): 203–207

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13 Responses to Wide-ranging review links artificial sweeteners with weight gain

  1. Nina 23 August 2013 at 12:39 pm #

    In my experience of weight loss, part of the journey was moving away from sweet tastes. This meant ditching as much sweetener (sugar and artificial) as possible. When I look at low carb sites in the USA, I find it amazing that the standard approach to mayonnaise and whipped cream is to add sweetener (presumably because these are sweetened with sugar in the standard American diet.) If you’re constantly accustomed to a sweet taste in sweet and savoury foods, then the body demands more.

  2. Alison 23 August 2013 at 1:17 pm #

    It’s a shame that sweetness in food and drink has become so normalised that most people can’t see a way of going sugar free that doesn’t involve consuming lots of artificial sweeteners. I used to take three sugars in my coffee and decided to wean myself off it by using slightly less each time. Just a few weeks after getting down to no sugar in my coffee at home I had a latte while I was out – it tasted sweet to me and I was sure my friend had put sugar it int. He hadn’t, I was just tasting the sweetness of the milk.

    A couple of months after cutting out all sugar from my diet I was drinking vodka and sodas in a restaurant. One round they brought me a vodka and tonic. I remember tonic being quite bitter before but once I’d cut sugar from my diet it tasted really sweet (undrinkable in fact).

    These days if I fancy some fruit juice anything more than 30ml in a pint of water is far too sweet for me. I’d probably struggle to drink a standard sweetness soft drink even if I was suffering from severe dehydration and it was the only source of water available.

  3. Robert 23 August 2013 at 1:29 pm #

    What I want to know is this: is there a difference between artificial sweeteners like Aspartame and so-called natural alternative sweeteners like Stevia (pure Stevia, not the mixed stuff). If the mechanism that may cause weight gain is the sweet taste that “alerts” the body, then it would seem that the sweetness of Stevia would do the same. And if artificial sweeteners do not effect a sense of satiety that causes one to stop eating or drinking, while sugar does, then would Stevia act more like the artificial sweeteners (not effecting satiety) or like sugar (effecting satiety.)

    If Stevia has the same problems as the artificial sweeteners, then it would seem the major problem is the taste of sweetness signaling the body, and it would be best to limit, in one’s diet, whatever TASTES sweet, regardless of the composition of the sweetener, or the calories.

  4. tess 23 August 2013 at 1:30 pm #

    Sad to say, these days one has to be careful even of researchers who say believable things — too often the publicly-accessible information is too vague to determine exactly what sweeteners were used, and how, and in whom. There’s a big difference between aspartame, which has sparked health problems in a large number of people, and saccharin which has been safely used for a century now. Is a cited study epidemiological (which proves NOTHING) or something happening in a metabolic ward…. And really — YOGURT? Hardly a natural food for rats, and the content of lactose to lactic acid is rarely well-defined! It’s too easy to design a study which will prove what you want to see — and the researcher you’re quoting obviously WANTS to dissuade the use of artificial sweeteners!

    A lot of us depend on health professionals who blog, to give us reliable discussions of technical information which is sometimes over our heads and VERY OFTEN only available to us in Abstract form, keeping us from learning the methods used in the “studies” so badly reported in the professional media! I appreciate this generous service supplied by many other researchers and doctors like you, Dr. B!

  5. Robert 23 August 2013 at 1:34 pm #

    Nina: your comment is similar to mine, and my experience is similar to yours. As I have gotten away from sweet tastes, I have found that attempting to drink something that I used to enjoy (ie. Stevia sweetened Root Beer) I find that it is now just too sweet and I don’t like it.

    The only thing I sweeten now is my tea or coffee and I sweeten less than I used to when I was more accustomed to sweet tastes.

  6. André 23 August 2013 at 2:16 pm #

    Weight is not the only problem. Aspartame produces a lot of radical oxygen damage and is linked to Alzheimers disease. Same as MSG and carragenan.

    Michael J. Foxx drank cans of light coke (=aspartame) a day. Look at him now.

    I think the real solution is that we learn sweet is bad. Fat and salt tastes better anyway, as far as I am concerned.

  7. Helen 23 August 2013 at 3:02 pm #

    I too would be interested to know if Stevia (the pure form – powdered leaf or water-based tincture) causes the same response as sugar or artificial sweeteners, i.e. promotes the release of insulin. I’ve been told by a doctor I know that it’s the only sweetener which does not do this, but I’ve since read contrary opinions. Anyone know?

  8. Jennie 23 August 2013 at 3:14 pm #

    This actually follows on from the series currently on BBC2. Episode 3 of 4 was shown last night, called (The Men Who Made us THIN) The subject of artificial sweeteners was the main topic in last nights episode. Endorsing Dr Bs article .
    This has been a fascinating series. (The Men Who Made us FAT) was shown last year and can still be watched on iplayer I think.
    I urge everyone to watch it!

  9. Fiona 23 August 2013 at 10:28 pm #

    Further to Jennie’s mention of yesterday’s BBC2 episode 3/4 of ‘The Men Who Make us Thin’, episode 2/4 is also still available on BBC’s series cach-up until 5 September.

    Also yesterday, again on BBC2, there was episode 3/3 of ‘The Men Who Make Us Fat’ (this is a repeat so not on the series catch-up).

  10. Peggy Holloway 24 August 2013 at 2:05 am #

    The word “insulin,” which is obviously at play here, was not mentioned once. Until the role of insulin in obesity and related symptoms is recognized there is no hope for reversing the obesity epidemic.
    I know I, for one, have an insulin “event” when I consume artificial sweeteners.

  11. Peggy Holloway 24 August 2013 at 2:06 am #

    In reply to question about stevia, I had an insulin spike/drop in response to drinking a stevia -sweetened soda.

  12. Liz 29 August 2013 at 12:17 pm #

    Where was I reading (here?) about insulin being released in our bodies at merely the thought of eating? An interesting point then that merely the thought of eating sweet things is enough to trigger a higher insulin response, so whether it’s sugar or artificial, if it tastes yummy and good, there’s going to be an insulin ergo fat-creating response? Sadly. I have pondered long and hard about the benefits of replacing sugar with sweeteners, based on the principle that life is too short and it’s jolly hard when you’re surrounded by cakes, chocolate bars ice creams etc, I have tried, somewhat successfully I hasten to add, to recreate sugar-free (ie artificially sweetened) and low carb versions of my favourite naughty dishes. ( I make a delicious sugar free ice cream to die for!). But I have wondered if these do create an insulin response. I haven’t started measuring my blood yet, got a glucose meter but not got a round tuit yet so don’t know. And I’m guessing we are all different, so some may be more sensitive to just the thought of something sweet than others, leading some to gain weight or halt or slow weight loss even using sweeteners.


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