|Artificial sweeteners - Could they really be less toxic and obesogenic than half of the blogosphere has it? The study at hand suggests so, but its significance is limited..|
If you've read my previous reviews of the corresponding papers, you will yet be aware that there is not a single human study to confirm that any of the "classic" artificial sweeteners (sucralose, aspartame & co) would have negative effects on the loss of body and fat mass during dietary restriction - an still you hear and read corresponding claims on almost every virtual corner of the blogosphere.
In this respect, the latest paper by Lone B Sørensen, Tatjana H Vasilaras, Arne Astrup, and Anne Raben is no exception. What is extraordinary, though, is that it describes a relatively tightly controlled single-blind 10-week parallel design study that provides convincing evidence that the association between artificial sweetener consumption and obesity that has been observed in epidemiological studies would be a good example to explain the term "reverse causation" [fat people buy diet products vs. diet products make lean people fat].
In the said study, 24 healthy, overweight subjects had to consume a specific minimum amount of either sucrose-sweetened or artificially sweetened foods and drinks daily.
"The subjects were assigned to 3 different levels of supplements according to their initial body weight: level 1, 2, or 3 corresponding to 60–75, 75–90, and.90 kg, respectively. The minimum intake of the experimental diet was regulated by the sucrose intake and corresponded to a sucrose intake of 125 g/d (level 1), 150 g/d (level 2), and 175 g/d (level 3). This corresponded to a total EI from sucrose supplements of 2.74, 3.29, and 3.83 MJ/d, respectively."The sweetener group received an equivalent amount (by weight) of foods and drinks, which resulted in an average EI of 694, 832, or 971 kJ/d at levels 1, 2, and 3, respectively. The artificial sweetener content of the intervention diet was 54% aspartame, 23% cyclamate, 22% acesulfame K, and 1% saccharin.
No low fat allowed: Some of the artificially sweetened products were low fat, so the subjects in the sweetener group were given additional butter or corn oil to keep the fat intake in the 2 intervention diets as similar as possible.In the sucrose group, ~70% of the sucrose came from drinks (average: ~1.3 L/d), and ~30% came from solids foods. About 80% by weight of the supplements were beverages, and ~20% by weight were solid foods. The beverages consisted of several soft drinks and fruit juices, and the solid foods consisted of yogurt, marmalade, ice cream, and stewed fruit.
The products were handed to all participants at the University without informing them about the specific content of sucrose and artificial sweeteners in the supplemented products was unknown to the subjects - all thought, they were consuming products with artificial sweeteners. Otherwise, they were advised to to consume their habitual diet ad libitum. And guess what happened!?
|Figure 1: Changes in body weight and fat mass (kg) and energy intake (in MJ) during breakfast, lunch and dinner measured on the one day all subjects had to spend in a metabolic ward (Sorensen.2014).|
The reason? Well, take a look at the left hand side of Figure 1. The subjects in the sucrose group did what some people claim would happen, if you consume artificially sweetened products: They ate more! Why? Well, because they were hungrier. Significantly hungrier; and that in spite of their 22% higher energy intake.
|Figure 2: The satiety response at lunch was (non significantly) less sustained in the sucrose group (full circles) compared to the artificial sweetener group (open circles) during the subjects visit at the metabolic ward (Sorensen. 2014).|
|Figure 3: 24h fatty acid oxidation after 10 weeks on diets with sucrose or artificially sweetened add-ons (Sorensen. 2014)|
In concert with the reduced fatty acid oxidation rates (see Figure 3) the remaining energy surplus of approx. 1,000kcal (that's the mere mathematical difference of total 24h energy expenditure during the stay at the metabolic ward and the corresponding energy intake) was obviously more than enough to fatten the subjects up.
- Sørensen, Lone B., et al. "Sucrose compared with artificial sweeteners: a clinical intervention study of effects on energy intake, appetite, and energy expenditure after 10 wk of supplementation in overweight subjects." The American journal of clinical nutrition (2014): ajcn-081554.