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I can’t quite believe that the last time I wrote a ‘weekly’ obesity research round-up was back before thanksgiving. Ah well. As I compiled this week’s roundup I am pretty familiar with it.

The old ‘should we tax sugar-sweetened beverages’ debate flared up again. There are many angles to tackle this question from, including philosophical, legal and human-rights angles. But Andeyeva et altook the efficacy angle, arguing that “an estimated 24% reduction in sugar-sweetened beverage consumption from a penny-per-ounce sugar-sweetened beverage tax could reduce daily per capita caloric intake from sugar-sweetened beverages [SSBs] from the current 190-200 cal to 145-150 cal, if there is no substitution to other caloric beverages or food. A national penny-per-ounce tax on sugar-sweetened beverages could generate new tax revenue of $79 billion over 2010-2015.” Thus ” A modest tax on sugar-sweetened beverages could both raise significant revenues and improve public health by reducing obesity.”

Of course, the problem is subtly alluded to by the authors themselves “if there is no substitution”. This design was a simulation design, and you can only simulate what the programmer has included as factors; we don’t yet know the effect of SSBs on appetite and whether they are compensated for, whether they are consumed because they are around in addition to what would normally be consumed, or whether they just a way of fulfiling an individual’s “natural” sugar intake. But, this is published the same week as Ng et al analyze the UK beverage consumption over time, and conclude that “This analysis implies that taxation or other methods of shifting relative costs of these beverages could be a way to improve beverage choices in Great Britain.”.

Is this case closed? No, an invited commentary from J.T. Winkler, argues that Ng et al’s analysis shows that ” a 10 %tax would reduce purchases by only 4·6 %. … It would not even cut sugar intake by a gram, only 12·6 kJ (3 kcal).” He notes that taxes on unhealthy foods are extremely unpopular in the States (where they are consistently rejected) and unpopular in Britain. He calls for clarification on the stance taken for  “sugar-sweetened” [i.e. added] drinks, like soda, and equally as sugary drinks with no added sugar, like fruit juice. The most interesting part of this article was a suggestion: drop the tax on low-calorie sweetened [diet] beverages, so that there would still be a price differential, but you would not be raising the prices on SSBs. Interesting… except that my personal feeling is that artificial sweeteners are not the answer. I think we have to stop looking for short cuts and accept that maintaining a healthy BMI will involve denial and some struggle, just get on with it. While the data do seem to be clear that diet drinks do not cause an insulin spike, they are not clear on the behavioural effects: do they increase hunger? Reduce satiety? If you give the same person a Diet Coke compared to a non-diet Coke , do they overall consume different calories that day? The next day? Over a long period of time? Do they expend the same energy? What about long term effects? The performance boost reported by simply swilling the mouth out with either type of drink suggests Pavlovian-style conditioning responses – this may mean that bodies respond to diet / SSB beverages in one way for a while, but that this can change. Long-term data on these obesity-related issues are not available.

Perhaps this is a personal plee. I have certainly noticed my hunger / sugar cravings (SO hard to distinguish between them) are less for cutting out artificial sweeteners. EVEN WHEN I DO NOT REPLACE THEM WITH SUGAR. Case in point: my oatmeal used to contain: 1/2c oatmeal; 1.5c water; 1/2 cup pumpkin, spices and 1 packet Splenda, served with 1/2c fat-free plain greek yogurt. I would want food about 20 mins later – by 90 minutes I was climbing the walls needing something. I took the Splenda out and did not replace it (it took me maybe 3 days to get used to the taste). Not only do I now prefer that taste, but immediately, I was full until lunch. I have replaced my diet coke at lunch with water, seem better. Most noticeably, if I have any chance of not eating M&Ms all darn night I can’t drink diet drinks. Which is shame, as they are delicious. But it definitely works.

 

And that was definitely a digression 🙂

 

Obesity rates in school children are dropping in NYC, despite flatlining or increasing elsewhere in the US. Is it because of their new school and home interventions? If this change is long-term, research says ‘no’, these interventions have diddly-squat that it meaningful to do with it – but is research always right? Ouch New Scientist.

Ahh… this article by Sofer et al caught my interest. What do we all know about carbs? Umm… don’t eat too many of them? Cut down on them? Especially at night, right? It so obvious, yawn, eat carbs in the day and you’ll burn them off, eat them for dinner and the insulin spike will remain throughout the night you’ll never burn fat they will turn immediately to fat and so on. Right? Well, although this (avoiding carbs at night) is a method I have used to cut overall calorie intake, when written in a sarcastic style, it might be clearer that this doesn’t quite make sense.

I would say I am cautiously a fan of the Atkins diet (caveats relating to baseline measurements and individual lifestyle factors… genetics too), but I do not like the way it is written about. Insulin is demonized; anything that ‘doesn’t’ produce an insulin spike it fine to eat in unlimited quantities. As Gary Taubes wrote (and I wish I could find this quite) “The only thing that can’t be turned into fat is fat!”. Right. Well, apple pie can’t be turned into apple pie, but ingesting it is likely the same as eating an apple, some sugar and some pastry. Data after data show the long-term effects of Atkins operate through behavioural changes, and increased compliance leading to lower calorie intake.

But, back to carbs at night. Apparently, it isn’t the answer. In a randomized trial, Sofer at al report greater weight loss when most of the day’s carbs are eaten at night. But again, my interpretation of that is that it is very behaviourally-mediated, as it is linked to higher satiety, lower hunger hormones and better metabolic outcomes related to glucose control (which are in turn related to diet adherence) than the diet with less carbohydrates at night.

As a purely speculative aside, I wonder if these effects result be because lower carbohydrate intake during the day mimics certain aspects of fasting? I don’t know. Just a thought.

Finally for this week (OK, month 🙂 ), Vogel et al write that orangutans gorge when food is plentiful, presumably to prepare for when it is scarce. During times of scarcity their metabolisms change their preferred fuel source from primarily glucose to primarily fat. I think David was baffled as to why I included this, but this is (as far as I am aware) one of the first lines of evidence that orangutans metabolisms share a lot of features and responses with human metabolisms. Which may be a super important first step in seeing if orangutans may be good models of human obesity… which, with their greater behavioural similarity (especially if we find the same in Bonobos) opens the door for all sorts of non-mice randomized controlled obesity trials we couldn’t do in humans.

 

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