Saturday, July 21, 2012

Does Juicing for Weight Loss Really Work?

Juicing to lose weight won't work for everyone. But if you are very disciplined about your eating habits, juicing for weight loss might make the critical difference for the success of your diet.
Before explaining how juicing for weight loss may work, I think it's a good idea to explain how any diet for weight loss, more specifically for fat loss (it's possible to lose weight without losing fat), actually works. The principle isn't all that complicated. Fat cells tend not to absorb fat and release fat to be burned elsewhere in the body at the same time.

And it turns out that what determines whether fat cells are absorbing fatty acids for storage or releasing fatty acids to be burned as fuel depends on the activity of two hormones known as lipoprotein protease, or LPL, and hormone sensitive lipase, or HPL.

LPL helps transport fatty acids into fat cells so they can be transformed into triglycerides for storage. Triglycerides stay parked in fat cells until they are broken down into fatty acids once again by HPL.

LPL is activated by insulin.  When insulin levels are higher, LPL is more active than HPO and triglycerides stay inside fat cells--sometimes even if you are consuming fewer calories than your body burns. Your body just gets those calories from places other than your fat cells, like your muscles.

When insulin levels are lower, HPL is more active than LPL and triglycerides are broken down into molecules that can escape your body fat. When this happens, the fatty acids released by your fat cells are used for fuel--sometimes even if you are consuming more calories than your body burns.

So what does juicing have to do with all of this?

Juices contain a form of carbohydrate called fructose. Usually fructose is decried as the enemy of all things healthful and holy, but up to about 50 grams (one tall glass of juice a day, or, better, three half-cup servings of juice a day) can be stored without insulin.

And that means that you can enjoy the energy boost for small amounts of juice as well as getting the antioxidants and potassium without interfering with the fat-burning benefits of eating less.

And, sorry, you still have to eat less to lose weight. There are no miracle weight loss juices or miracle weight loss foods or miracle weight loss pills, either. But if you are going to snack between your reduced-calorie meals, small amounts of juice, up to 4 fluid ounces (120 ml) every couple of hours, are a great way to keep up your energy without interfering with fat burning.

I know this goes against both the calories in-calories out concepts of weight loss and the Gary Taubes fructose-is-of-the-Devil school of weight loss. But try it. You do the hard work of losing weight by eating less. But fruit juices can help you keep your energy so you stay focused and stick to your plan.

Photo credit: Midori, via Wikimedia Commons.

How Good Juices Are Made Bad

In my post on the real joy of juicing, I explained how juices are a great way to get some of the 5 to 9 servings of vegetables and fruit we need every day to stay healthy. They provide a variety of nutrients without the fuss of buying, storing, and preparing up to 9 different kinds of plant food every day, and the right juices (I'm partial to vegetable juices for this) help control appetite and indirectly control weight. Fresh juices stored properly provide antioxidants that partially cancel out poor food choices. But even a good juice can be bad for you if it's loaded up with chemicals your body just tolerate. Here's what to look for on the label and why.
Not everyone is equally sensitive to every chemical additive that manufacturers will put in juice, but some people are very sensitive to certain chemicals added to juice. For instance, if you are allergic to aspirin, or if eating certain kinds of fruit makes you break out, you are likely to need to avoid the additive tartrazine.


Some US food manufacturers identify tartrazine by its older name F D & C Yellow 5. In the European Union, it's usually labeled as E102. Tartrazine adds a brilliant yellow color to orange, peach, and mango juices. It's most likely to be added to juices made from fruit harvested in the tropics, where excessive warmth keeps fruit from turning color as it ripens. Until recently, Kraft Macaroni and Cheese was colored with tartrazine.

Tartrazine is notorious for causing allergies with unusual symptoms, such as dizziness, slurred speech, attention deficit, or migraine in addition to runny nose and/or skin irritation. Ironically, many antihistamines are also colored with tartrazine. If you are allergic to prunes, raisins, curry powder, oregano, dill, or cilantro, you need to avoid any juices that contain tartrazine.

Sodium benzoate, which is labeled in Europe as E211 is a preservative that is chemically very similar to benzoic acid, which occurs naturally in apples, plums, and cranberries. It's made by mixing benzoic acid and lye. In this form it slows down the metabolism of decay-causing bacteria, without adding any acidity to the flavor of the food or beverage to which it's added.

It's easier to give you a list of foods that don't contain sodium benzoate than it is to give you a list of foods that do. Nearly any packaged or bottled food or beverage will contain sodium benzoate, and most of us that's not a problem. Only about 1 in 300 people is sensitive to it. But for 1 in 300 people, the allergies caused by the chemical can be very serious.

Sodium benzoate causes many of the same symptoms as allergies to aspirin. It adds to the allergenic effects of aspirin and also to any allergenic effects of tartrazine, which are described above. Sometimes it's the combination of eating Thanksgiving cranberries (which contain benzoic acid) and eating a food that contains sodium benzoate and taking an aspirin that produces the allergic reaction. And sodium benzoate also increases any side effects caused by red dyes, such as Allura Red AC and Ponceau Red 4R.

Sodium benzoate is especially detrimental when it's added to juices you drink for their content of vitamin C. It reacts with vitamin C to form benzene, the cleaning solvent, not the automobile fuel. Regulatory agencies around the world pooh-pooh the potential of sodium benzoate to cause health problems in juice, but you get as much benzene from an 8-ounce (240 ml) glass of orange juice to which sodium benzoate has been added as you do from pumping a tank of gas or 24 hours of exposure to second-hand tobacco smoke.

Speaking of red dyes, Ponceau 4R (in Europe, E124) is the dye most often associated with ADHD. It's never the sole cause of ADHA in children or teens, but it's often one more burden on a stressed growing brain. If you want to avoid Ponceau 4R, make sure any strawberry or cherry juice you drink is either made at home or at least labeled as "all natural" or "organic."

Also in the family of allergy-inducing red and yellow dyes are Allura red (E129), carmoisine (E122), and Sunset Yellow (E110). The main difference among these dyes is how rapidly they react at body temperature. If you're loading up on dyes and aspirin, however, all of these chemicals have more or less the same effect.

It isn't just red and yellow dyes that can cause problems with allergies. A Gatorade-green dye called Quinonone Yellow (E104) can also trigger symptoms similar to aspirin allergy. About 1 in 100 people will experience a mild allergic reaction when juice containing Quinolone Yellow is spilled on the skin. About 1 in 300 people will experience moderate to severe asthma or hives after drinking a beverage (or eating smoked haddock) colored with the chemical. And about 1 in 1000 people will develop migraines, attention deficit, or otherwise inexplicable emotional symptoms after consuming the dye.

The best way to be absolutely, positively certain your juice doesn't contain any of these chemicals is to make your own juice. I'll have more to say about economical ways to enjoy juicing in a later post.
Image credit: Salimfadhley via Wikimedia Commons.



The Real Joy of Juicing

It has become practically an article of nutritional faith that everyone needs to eat 5 to 9 servings of fruits and vegetables every day. But juicing is the easiest way to be sure you get all the plant foods a healthy body needs.

What's special about juice? It's convenient. It tastes better because more of our senses are involved when we drink juice than when eat chunks of fruit and veggies. It has some special advantages for appetite control and for minimizing fat storage, and the right juices (I'm partial to vegetable juices) can cancel out some of the ill effects of poor food choices.

An obvious advantage of drinking juice is convenience. It takes time to buy fresh veggies and fruit. They have to be taken home, washed, and refrigerated or used right away to avoid spoilage. If you are going to eat 5 to 9 servings of fruits and vegetables every day, it's only natural to want 5 to 9 different fruits and vegetables every day, and that only adds to the burden of choosing them at the market and preparing them at home. And if you are eating out once or twice a day, chances are you aren't going to get the 9 servings of veggies your body really needs without paying a lot more for your meals. Juice is an easy way to get your fruits and veggies without spending hours and hours preparing them, and without having them go bad in the frig.

But that's not the only advantage to freshly squeezed juice. Juices usually taste better than the fruits and vegetables from which they are made. That's because juices are liquids, and liquids come in contact with the entire tongue. We taste the sweetness of a juice at the tip of our tongues at the same time we taste the aromatics in juice at the back of our tongues.

Getting the whole tongue involved in tasting juice brings out flavors that just can't be perceived in the whole veggie. Even vegetables like broccoli and cabbage (if you don't have a special sensitivity to the sulfur compounds in them) turn out to have sweet overtones you can taste when the juice lingers on the tip of your tongue. Fruit juices pack a lot of their flavor in compounds that have to smelled, rather than tasted, and liquids release their aromatics to the nose a lot better than fruit flesh you chomp on down. And juice even helps you lose weight. Here's how.

Juice, Hunger, and Weight Loss

Juices consist of billions of tiny particles suspended in water. Those particles have to be digested before the stomach sends the juice down to small intestine. This makes both the juice and any other food linger longer in your stomach, helping you feel full longer, so you eat less.

The chunks of fruit and vegetable you eat also linger in your stomach and help you stay full. The advantage of juice over "whole" fruits and vegetables is that there are many more tiny bits of fiber that the stomach can sense. The stomach may send bigger chunks of fruits and vegetables only partially digested down to the gut, but it will do a more thorough job of digesting tiny particles. You get more of the plant chemicals, vitamins,minerals, and enzymes in the fruit or vegetable, and you feel more satisfied.

And drinking juice rather than eating chunks of fruits and vegetables also helps you with weight control at the "gut level" of digestion. The small intestine is lined with stretch receptors. When a large amount of food of any kind finds its way into the small intestine, which is just below the stomach, the stretch receptors send a message to the brain that sends a message to the pancreas to release more insulin.

This prepares the body to store sugar. But insulin also stores fatty acids. If you eat foods that bloat, your whole body is primed for fat storage. If you eat plant foods in their liquid form, your body will still find a way to store excess calories, but you at least will have a chance to burn them before insulin locks them in your belly and buttocks fat.

Juicing also helps cancel out other poor food choices. If you down a cheeseburger and fries and a glass of juice, for example, the antioxidants released by the juice neutralize at least some of the pro-oxidants generated by the dump of fatty acids and sugar into your bloodstream after you chow down on fast food. It's better to eat only healthy food, of course, but juice helps.

Variety stimulates appetite. The more different kinds of juice you drink, the more you will enjoy them. I have a personal bias for freshly squeezed juice over bottled juices, but any kind of juice can enhance a good diet--as long as it's made with no sugar added and without juice additives.

Image credit: Scott Bauer (USDA), via Wikimedia Commons.