What should you cut out of your diet to be more healthy? Everything. According to the most popular diet books on the market, there's barely a food on Earth that's safe to eat. But what is the actual benefit of these diets? Here's what science has to say.
10. Cut Out Wheat to Slim Down
The Books: The Wheat Belly Fat Diet, Wheat Belly
The Claims: Wheat is making you fat! And not just fat, but fat around the tummy, which is the worst kind of fat! Belly fat itself puts you at a higher risk of cancer and other diseases. And we can cut our weight and cancer risk way down by cutting wheat out of our diet. This is especially hard because, since the 1970s, Americans have been pushed to eat more "whole grains" in order to be healthy. But since the 1970s, Americans have gotten steadily fatter on this supposedly healthy diet. Is there any doubt that wheat is ruining our health?
The Facts: Most "wheat belly fat" books contain persuasive book jacket blurbs that stress how obesity has gone up in the decades since people began eating a carb-based diet. But correlation doesn't necessarily mean causation. One possible explanation for the national weight gain is the fact that the median age of the United States population has also gone up, and no matter what, we gain fat as we age. In fact, age is a major factor in why we gain belly fat. Eat no wheat whatsoever, and you'll still pack on a bit more belly fat as you get older, even if the fat is internal. (Sorry.)
It's possible that belly fat may be more unhealthy than regular fat. Abdominal fat cells tend to boost the production of certain hormones which aren't healthy. But belly fat isn't the only problem. It turns out that "gluteal fat" (AKA the fat on your butt) promotes inflammation and insulin resistance. In other words, all extra fat can be bad. Belly fat isn't necessarily worse than any other kind of fat.
Even if belly fat is especially unhealthy, wheat might not be the main culprit. If you want to lose belly fat, you might want to look at saturated fats. In one study, men who ate muffins made with saturated fats gained more abdominal fat than men who ate muffins made with unsaturated fat. There is even one carefully-done study that suggests carbohydrates might lower a person's amount of belly fat. Men with a daily diet that contained 10 grams of soluble fibre lost more visceral fat over 5 years than men who didn't eat the soluble fibre. Oats, barley, and beans all have soluble fibre. A warning -- this reduction in fat was a 3.7 per cent reduction. There are no miracle diets that will simply take away your belly. Nor, really, do there need to be.
9. Get Thin and Healthy by Controlling Your Body's pH Balance
The Books: The Alkaline Cure, Eating the Alkaline Way, The Amazing Acid Alkaline Cookbook
The Claims: There are a lot of "alkaline diet" books that caution people to stay away from acidic foods, claiming that our acidic diet makes us sluggish, destroys our bones, and makes us prone to disease. Most of these books make uncontroversial health recommendations, asking people to drink water with lemon instead of coffee, cut out the alcohol, eat more vegetables, and eat goat cheese instead of cow's cheese. Adhering to alkaline-diet-approved foods will make the body alkaline. Cancer cells do not thrive in an alkaline environment. Cutting out the acid is also supposed to prevent bone loss.
The Facts: Although a steady diet of alkaline foods is meant to make the body more alkaline, blood pH is regulated by the kidneys. Diet doesn't change the pH for an appreciable length of time. A review of material studying the health effects of alkaline diets states, "There is no substantial evidence that this improves bone health or protects from osteoporosis." The review states that there may be some benefit to the diet, but the benefits are probably just from adopting a healthy diet. More tests are needed before the health effects of a specifically "alkaline" diet are conclusive. Meanwhile, cancer research sites stress that an acidic diet does not cause cancer. The alkaline diet is not a cure. It is, at best, just healthy.
8. Probiotics Will Keep Our Insides Ecologically Balanced
The Books: Probiotic Rescue, The Probiotic Revolution, Fermented Foods for Health
The Claims: Fermented foods have become very trendy. Why drink tea when you can drink kombucha? Why drink milk when you can eat yogurt? Probiotic foods help keep us full of "good" bacteria. These bacteria help us with digestion, treat irritable bowel syndrome, calm inflammation, and thin us down by stopping our carb cravings.
The Facts: Foods might not need to actually be fermented to be helpful. A study of irritable bowel syndrome sufferers had them drink either milk or yogurt. The subjects stated that they found relief not just with yogurt, but with plain nonfermented milk. And probiotic or not, the relief was described as merely "adequate." Fermentation is not a wonder cure.
Even if probiotics were wonder cures, they wouldn't be present in any pot of yogurt - even if it is labelled as "probiotic." Laboratory studies on the effects of bacteria maintain strict quality control, so scientists are sure that people are getting an effective amount of a certain kind of bacteria. Companies, and home fermenters, do not have the same quality control systems. A survey of probiotic products found that most companies don't really make any effort to measure how much of this "good" bacteria goes into the product. They also don't make any real effort to keep it alive when it's in there. Probiotic foods are often just foods full of a small amount of dead bacteria.
7. Raw Foods Will Cleanse You
The Books: The Raw Food Detox Diet, The Raw Cure, Raw Food Cleanse
The Claims: Cooked food allows toxins to build up in your body! These toxins cause you to be sluggish and increase your risk of cancer. Raw foods can cleanse you of these toxins. Cooking also destroys key nutrients and denatures important enzymes that make your body healthier. Finally, certain foods are not meant to be combined with other foods. For example, fruits are not to be mixed with vegetables if you want to get all the nutrition to be harvested from them.
The Facts: First of all, there are organs that "detox" a body already. They are called the liver and the kidneys. If they aren't working, a raw carrot isn't going to help. Only an organ transplant will help. While some studies did find that raw vegetable consumption decreased cancer rate more than cooked vegetable consumption, others contradicted them. A study of bladder cancer found that cooked vegetables can decrease the rate of cancer while raw vegetables do not.
Cooking does destroy nutrients, but nutrients like the lycopene in tomatoes can be more completely absorbed into the body if they are cooked, especially if they are cooked with some kind of fat. As for enzymes, their existence is dependent on a lot of factors. Heat is one, and pH is another. Considering that is no way to digest anything without giving it an acid bath in your stomach, few enzymes get "absorbed" into the body whether they have been heated or not. Finally, there is no evidence to support that certain combinations of common fruits and vegetables -- or any other food -- need to be avoided.
6. Sugar Consumption is a Drug Habit You Have to Kick
The Books: Suicide by Sugar, Sugar Blues, Sugar Nation, Overcoming Sugar Addiction
The Claims: Sugar is not just a bad food; it's an addictive drug. Studies done on lab mice show that brain response to sugar addiction is similar to brain response to cocaine and heroin.
The Facts: No one digs into a piece of chocolate cake thinking it's good for them, but it's not heroin. It's fair, in some cases, to use rat behaviour as an analogue for human behaviour. It's still important to make sure, having obtained the results of a rat study, to make sure humans react the same way. Lab rats love sugar. Multiple studies show that lab rats go through an addiction cycle of eating, withdrawal, and craving sugar -- sometimes even more than they do cocaine. Sugar also lights up reward pathways in their brains.
However, studies done on humans give us a different picture. If sugar were addictive in humans you'd expect these effects: fasting should increase craving of sweet foods in particular; obese people should crave sweet foods more than other foods; and a person's initial diet, not social or economic forces, should be the highest predictor of sugar addiction. None of these scenarios are typical. What's more, if sugar addicts are given opioid antagonists, which block brain receptors that respond to "addiction" chemicals in the brain like opioids and endorphins, we should see sugar withdrawal symptoms. In humans they don't. People eat too much sugar, and some may crave it, but sugar is not a physically addictive substance for human beings.
5. Superfoods Will Save You From Everything
The Books: Superfoods Rx, Super Immunity Foods
The Claims: Not only should you eliminate many foods from your diet, you should shift your staple diet to "superfoods." These foods have special antioxidants that will prevent cancer. They will boost your immune system. They will speed up your metabolism to help you lose weight, too! Anything is possible if you live on green tea, blueberries, and kale.
The Facts: It's true that antioxidants do, in some studies, protect cells in laboratories from cancer. The antioxidants pair with free radicals - molecules with unpaired electrons. These molecules might otherwise pair with our DNA. Free radicals damage the body. Free radicals damage other things as well, including microorganisms like viruses and bacteria which have invaded our bodies. It's not a good idea to wipe free radicals out, even in theory. And while some studies show that antioxidants prevent cancer, others show that they keep cancer cells alive and decrease the effectiveness of chemotherapy. Cells alone on a plate in a lab respond consistently well to antioxidants, but cells in the body are more complicated.
Food is more complicated as well. To begin with, "a blueberry" isn't a precise dosage. In laboratory tests, scientists give cells (or animals) extracts from these superfoods. It isn't always possible to match, via actual food, the amount of extract given to animals in lab. To get the maximum amount of antioxidant health benefits from green tea, you need to drink several cups (not mugs) per day. A study that looked at green tea extract's effect on mice predicted that, to use it to increase human metabolism and lose weight, you would need about seven cups a day. If that still sounds like a good idea, beware. The tannins in the tea decrease your ability to absorb folic acid -- a form of vitamin B that you need.
Superfoods are good for you, but they can't be used as cancer-preventing drugs. Drugs are purified versions of certain effective ingredients, isolated and given out in precise doses. Food is a big sloppy pile of different molecules that will interact with your body in many different ways.
4. Juices Will Cleanse You and Shrink Your Waistline Like Magic
The Books: Skinny Juices, Fat Sick and Nearly Dead
The Claims: Juices help you cleanse yourself and detox! They're healthier than whole fruits, and give you more nutrients!
The Facts: The body has kidneys and a liver to detox and cleanse itself. There is no cup of anything that will work the way these organs do. Nor is there any evidence that making something into juice allows you to get more nutrients out of it.
There are some real problems with consuming only juice. Fresh-squeezed juice is a haven for bacteria, so making a big batch of juice and saving some for later can be problematic. Fruits are full of sugar, and so people on juice cleanses can consume too much sugar without noticing. Too much kale can exacerbate hypothyroidism, too much lemon can erode the enamel on your teeth. The sugar in fruit can do a number on your teeth, as well. Juicing isn't terrible, but it's an extreme change in diet - more extreme than any other diet on this list - and needs to be done very carefully.
3. Paleo Diets Make Us as Healthy as Cave People
The Books: The Paleo Answer, The Paleo Solution, Primal Body Primal Mind
The Claims: Human beings evolved to eat the diet they ate during the stone age - no milk, or wheat, or processed foods. No cultivated foods at all. If we want to be like lean, ruthless, healthy hunter-gatherers, we need to eat seeds and nuts, roots and berries, fish and meat. The food of today is making us fat while depriving us of nutrition. We need to eat only the food we evolved to eat if we're going to be healthy.
The Facts: We're still evolving. A surprising amount of evolution happens in a few thousand years. Many humans evolved lactose tolerance, which allows us access to the calcium and calories in milk that our ancestors would have loved to be able to eat. By settling down we also managed to start eating fibrous legumes, packed with nutrients and protein and low in fat. Many paleo diets forbid these for the sole reason that they're pre-historically incorrect. But historical accuracy isn't the same as nutrition.
What's more, we weren't the only ones evolving. Even eating lean meat and tubers -- even digging and raising and hunting all of those things in your own back yard -- won't let you eat the way paleolithic hunters did. Almost all the food we eat or raise these days has been modified from its wild form. Some of that modification was done thousands of years ago, by the very ancestors this diet is supposed to imitate, and much of it has made the food better. Corn, for example, has gone from a weed that was barely worth picking to a staple that provides us with good nutrition. For that matter, paleolithic hunters weren't the lean, healthy people we imagine. Excavations of hunter-gatherers have revealed that they had all kinds of health problems, including the fatty build-up in the arteries that still plagues their descendants.
2. Go Vegan and Go Ultra-Low-Fat
The Books: Forks Over Knives, The China Study
The Claims: Forks Over Knives is not so much a book as a constellation of media, including a book, a cookbook, and a documentary about the diet formulated by Dr Caldwell Esselstyn. The centrepiece of all three books is The China Study. This famous study showed that rural villagers in China, who ate a mostly-vegan diet had extremely low rates of cancer and cardiovascular disease. As the prosperity and westernization of their area increased, and the population ate more meat and more fat, the disease rate increased.
In the documentary, one woman on the Esselstyn diet seems to fight off breast cancer with the diet. Other dieters halt or reverse coronary artery disease with the diet. Their success is presented as the result of giving up all meat, meat products, and added fat. Not only are all animal products off the table, but vegetable oils, nuts, and avocados are as well. Dieters "fry" their food in broth or water.
The Facts: The documentary never actually claims that a low-fat vegan diet stops cancer, which is good, because it does not. There is some evidence that people on vegetarian diets have a better survival rate once they already have colon cancer, but most of the studies done on a vegetarian diet note that vegetarians already tend to be more health-conscious than the rest of the population. Another study comparing vegetarians and meat-eaters noted that vegetarians have lower rate of heart disease, but tend not to have a lower mortality rate for other diseases. As for the reversal of symptoms of coronary artery disease, a group of people on a carbohydrate-rich diet created by Dean Ornish also reversed their symptoms. Though also low-fat, the Ornish diet allows for egg whites and cheeses.
Although experts agree that The China Study shows very strong correlation between an increase of fat and meat in diet and an increase in cancer and heart disease, the study has some problems. Critics point out that many factors, including the intake of plant protein, increased the rate of cancer. They believe that the data has been selectively picked over, and deliberately interpreted in a way that overemphasizes the negative effects of animal proteins.
Even Dr. Colin Campbell, the author of the survey, openly admits that there is no data showing that going 100 per cent animal-free is better than going 95 per cent animal-free. The China Study is also not the only study that looks at diet and population health. Studies of the Inuit and Masai people show they consume a lot of animal protein while maintaining good overall and cardiovascular health. The French, meanwhile, eat a lot of saturated fat and have a low rate of cardiovascular disease. Although an incredibly low-fat vegan diet is (generally) good for you, it's not a miracle cure, and you can get similar effects without going vegan.
1. Grains Are Killing Your Brain
The Books: Grain Brain
The Claims: Grains cause inflammation. Inflammation causes neurodegenerative diseases. Alzheimer's, Parkinson's, ADHD -- they can all be avoided if we just stopped overloading on carbohydrates (even whole grains) and ate more fat. A high fat diet might even help us grow more brain cells.
The Facts: Forks Over Knives and Grain Brain end this list because they seem to be directly opposed to each other. In fact, the Forks Over Knives website has a page full of links rebutting the arguments made in Grain Brain.
Other scientists have pointed out that the evidence that seems to advocate a low-carb, high-fat lifestyle,is inconclusive. One study linking diet and Alzheimer's makes it clear that, although obesity and diseases like Alzheimer's are related, obesity hasn't been proven to cause Alzheimer's. Another study, meant to show the correlation between gluten and cognitive decline, involves only 13 patients with celiac disease. The book seems to take preliminary studies as definitive proof.
The book does, however, make good points about how hard Americans were pushed to make grains a staple of our diet. And it shows that grain may not be the wholesome, healthy food we believe it to be. Taking some grains out of a diet, and replacing them with vegetables, would be pretty healthy. Still, although it certainly benefits people with celiac disease to get off grains and gluten, there's no definitive evidence it will save anyone's brain.
The point of this list is not to poke fun at scientists for disagreeing with each other. Nor is it to claim that most of these diets aren't beneficial. With the possible exception of juicing, choosing a random diet on this list and adopting it would probably improve the health of anyone reading this. These books are right to point out that most people aren't aware of how much fat, sugar, processed food, and refined carbohydrates they eat or how bad those things are for their health. To get really healthy, most of us need to radically change our diet, not just add a couple of salads a week. That said, there is no diet that can make you younger, cure or prevent cancer, magically give you limitless energy, or fix your brain. There are also no foods that are equivalent to meth or toxic waste. And, finally, there was no golden age when everyone was "natural" and "healthy." Humans have always had diet problems; what's changed is that now we have scientific investigations that can help us understand them.
[Sources via: Lifestyle Factors And 5-Year Abdominal Fat Accumulation, Abdominal Fat and What To Do About It, Median Age, Overfeeding Polyunsaturated and Saturated Fat, JCEM, The Alkaline Diet, 10 Persistent Cancer Myths Debunked, Effects of Probiotic Fermented Milk on Symptoms and Intestinal Flora, Probiotic Bacteria: Survival in Dairy Foods, Evidence for Sugar Addiction, The Plausibility of Sugar Addiction, Best Way to Eat Fruit, Is Juicing Healthier, Trouble Ahead, Superfoods and Cancer, University of Maryland Medical Center, Green Tea Extract Protects Obese Mice, Cancer Research UK, How to Really Eat Like a Hunter-Gatherer, The French Paradox, Intensive Lifestyle Changes for Reversal of Coronary Heart Disease, Symposium on Plant Food and Public Health, UCSF, Cognitive Impairment and Celiac Disease, This is Your Brain on Gluten, Raw Versus Cooked Vegetables and Cancer Risk.]
This story has been updated since its original publication.