It’s that time of year again, where many make, but only a few keep, their New Year resolutions. The most common one is to lose weight. Short of cutting off a leg (which will have you down a good thirty pounds or so overnight) one of the silliest things one can do to achieve this goal is to go on a so-called ‘juice cleanse.’ Quite apart from the insipid and euphemistic name (what are you cleansing exactly?) the macronutrient makeup of a juice cleanse can (a) have unfortunate effects on one’s health and (b) actually be quite unhelpful for long-term weight loss. Consider my humble plea, gentle readers, and opt for a different form of self-flagellation in the New Year. I recommend classes in biology.
First, because not everyone has been subjected to ten exceedingly painful weeks of just that, we should talk about what is involved in a juice cleanse. A handy Google search of popular juice cleanses seems to indicate that these ‘juices’ are basically a concoction of pulverized fruit and vegetables in a usually very expensive bottle. Basic macronutrients in fruit and vegetables include fiber (obliterated by the juicing process), water, excessive amounts of popular water-soluble vitamins (the recipe for expensive urine) and fructose. Yes, fructose, and in much greater quantity than when eating whole fruits, as those expensive blenders combine, reduce, and distill the juices of many fruits.
Fructose is a simple monosaccharide that is an isomer of glucose. For you non-chemists out there, that’s table sugar in a fedora. Different, but not that different. In fructose’s favor, it has a lower glycemic index than glucose or sucrose as it does not actually trigger insulin production and it has previously been recommended as an alternative sweetener for diabetics. Not commonly advertised is that high levels of fructose consumption have been linked to rather icky health complications such as obesity (whoops!), insulin resistance (what diabetics have), and heightened LDL (‘bad’) cholesterol. In a recent study in mice, consumption of fructose water versus consumption of soft drinks (both regular and diet) showed that the former resulted in increased ‘adiposity,’ i.e. an increase not only in weight but specifically in fat. This alone should start alarm bells ringing.
Furthermore, long-term exposure to a high fructose diet wreaks merry hell on a variety of important organs. For instance, it can result in decreased metabolic efficiency of the liver, increased inflammation of fat tissue as well as stimulating the production of visceral fat (the fat around your heart that chokes it until you die), and intestinal inflammation (gives you the runs). Another interesting effect of a high fructose diet is the smackeroo it delivers to one’s central nervous system. In the long term, increased insulin resistance and diabetes are tied to a decrease in neuronal health and synaptic plasticity (ability to form new memories) and such diseases as Alzheimer’s. A more likely outcome is the development of leptin resistance. Leptin is the hormone that indicates satiety so a high fructose diet, roughly speaking, can make you feel less ‘full’ over time. Basically you’ll want to eat more.
The lesson to take from this is not that fruit is bad. Fruit is great. Vegetables are great. They are an important part of a balanced diet. My point is that the claims of a juice cleanse, while they may work in the short term due to a drastic decrease in caloric intake and the loss of water weight, the long term effects of high fructose consumption are not only the opposite of the desired effect of weight loss but, most importantly, it can be quite dangerous. If you are concerned about the post-holiday expansion of your waistline, I recommend a balanced diet, and exercise that makes you feel good. And for crying out loud, spend your money on something that isn’t so damaging to your health: a box of chocolates, perhaps?
Jane Makin recently graduated from the University of Chicago and is working for the Ben May Department for Cancer Research. This piece is based on her own research and represents her own views.