Monday, 11 August 2014

Artificial sweeteners are making you fat

'Diet soft drinks are definitely not for people trying to loose weight.
 It is interesting that in a world of 0 calorie foods and drinks we as a nation appear to be gaining weight. I have always seen weight loss/gain is an equation (energy in – energy out = weight gain). Therefore, one would assume if you replaced a 200 calorie cup of juice with a 0 calorie soft drink you would lose weight. So why is there not an epidemic of skinniness with all these low calorie products?
I decided to do some research.
 What I found was that far from helping in weight loss,  ‘diet’ drinks may actually contribute to weight gain. 
How can something with 0 calorie make you put on weight? It does not make sense.
It all has to do with appetite.
Out appetite is what keeps us the weight that we are. For the majority of people appetite allows us to stay within a relatively stable weight range (slowing increasing as we get older[1]). Appetite is also the reason why many people put weight back on after a diet (and then some usually). One is able to fight ones intrinsic appetite for a time while one is losing weight, but fighting it for the rest of ones’ life can be incredibly draining[2].
Another thing that points to appetite (i.e. how much we eat rather than the calorific value of what we eat) as the cause of obesity is the “French paradox. The French diet is relatively high in ‘bad foods. There is lots of saturated fat, yet the rates of obesity are a lot lower than the United States. Why? One of the simplest reasons is while they may eat proportionally more high calorie foods, they eat smaller amounts[3] .
So the key to maintaining a healthy weight is Appetite. So why do some people have bigger appetites than others and what role do artificial sweeteners play in appetite?
It has been shown that one of the key players in appetite is sugar. Sugar increases the ‘tastiness’ of food and can actually be addictive triggering the same neuronal pathways as serious drugs of addiction like cocaine[4]. So why would taking sugar out of something make us fat? Because it is not actually sugar that does this, it is sweetness. Our tastebuds are fooled by the sweet messages and the pleasure centers are activated. But our stomachs are not fooled by these imposters[5]. This means the sweetness sends a signal to the brain stating “eat more” whereas the stomach sends a signal stating “there is nothing in here keep on going”. It is confusion between the messages between the brain and the stomach,  that may encourage us to overeat
How it is the sweet taste that actually stimulates appetite was elegantly shown in an experiment where men were given artificial sweeteners as a drink or in a capsule. When they were given 280ml sweetened water their appetite for other foods increased, wheras when they were given in capsule form with 280ml plain water (so the sweetness was only released on arrival to the stomach) there was no change in appetite[6].
Other experiments have shown that changing from regular to diet soft drinks either has little effect on weight or increases weight (Yan, 2010 cites multiple examples) . Consumption of sweetened drinks by young children (I wonder how a study giving these things to children got through an ethics committee, but anyway…) was shown not to significantly decrease total calorie consumption, but make them more picky about what foods they would eat[7] (i.e leading to preference for less nutrient dence foods and thus paving the way for problems in the future) (sugar sweetened drinks decreased calorie consumption in the next meal and also made them more picky).
One theory as to why people may actually gain weight on by consuming zero calorie sweetners is that the disconnect between sweetness and actual calorie rewards teaches out brains that sweet does not equal calories. Therefore when we actually consume a calorie containing sweet item our brains tell our appetite that it does not have calories and we should continue eating[8].
Therefore one of the key ways to reduce appetite is to decrease the sweetness of ones diet. ‘Diet’ drinks do exactly the opposite of this. The research is quite clear. They do not help decrease appetite and will not help in long term weight loss. (since many of the studies proving this were done quite a while ago it seems a bit misleading that they are still allowed to market them as diet products).
Next time you are feeling thirsty and want something ‘diet’ go for a cup of water, or an unsweetened cup of tea or coffee. If you must have something sweet have a glass of juice. Don’t reach for the ‘diet’ drinks, all that the ‘diet’ is, is clever marketing. It will not help you achieve sustainable weight loss.

[1] Dariush Mozaffarian, M.D., Dr.P.H., Tao Hao, M.P.H., Eric B. Rimm, Sc.D., Walter C. Willett, M.D., Dr.P.H., and Frank B. Hu, M.D., Ph.D Changes in Diet and Lifestyle and Long-Term Weight Gain in Women and Men, N Engl J Med 2011; 364:2392-2404

[2] Mann, Traci; Tomiyama, A. Janet; Westling, Erika; Lew, Ann-Marie; Samuels, Barbra; Chatman, Jason Medicare's search for effective obesity treatments: Diets are not the answer. American Psychologist, Vol 62(3), Apr 2007

[3] Rozin P, Kabnick K, Pete E, Fischler C, Shields C. The ecology of eating: smaller portion sizes in France Than in the United States help explain the French paradox. Psychol Sci. 2003 Sep;14(5):450

[4] Ahmed, Serge H.; Guillem, Karine; Vandaele, Youna, Sugar addiction: pushing the drug-sugar analogy to the limit , Current Opinion in Clinical Nutrition & Metabolic Care:

July 2013 - Volume 16 - Issue 4 - p 434–439

[5] Qing Yan Gain weight by “goingdiet?”Artificial sweeteners and the neurobiology of sugar cravings Neuroscience2010 pp.101-108.

[6] Black, RM, Leiter LA, Anderson GH, Consuming aspartame with and without aftertaste: differential effects on appetite and food intake of young adult males. Physiol Behav, 1993;53: pp459-466.

[7] Birch LL, Mcphee L, Sullivan S, Children’s food intake following drinks sweetened with sucrose or aspartame: time course effects Phisiol Behav. 1989 Feb; 45(2):387-395

[8] Smeets PAM, de Graff, C, Stafleu A, Van Osch MJP, Van der Ground, J. Functional magnetic resonance imaging of human hypothalamic responces to sweet taste and calories. Am J Clin Nutrition.  2005; 82:1011-1016

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