Meat Can Cause Stress Hormone Levels to Rise and Testosterone levels to Drop

A critique of the scientific validity of the dietary advice in Men’s Health magazine discovered nuggets claiming meat can give men “a testosterone boost,” but we’ve known for a quarter century that a meal with that much fat can drop testosterone levels by nearly one-third within hours. In fact, a significant drop of both free and bound testosterone in the bloodstream occurs within just one hour of it going in one’s mouth, whereas a low-fat meal of mostly carbs has no such effect. Based on in vitro studies on the effects of fat on testicle cells in a petri dish, researchers suspect fat in the blood may actually suppress testosterone production in real time. If you feed people lots of eggs and meat, including fish and poultry, and then switch them to a diet with bread, fruit, vegetables, and sugar—but about the same amount of fat—all their testosterone levels go up. Even more importantly, however, all their levels of cortisol, a stress hormone produced by our adrenal glands, go down.

Having low stress hormone levels is good, because high cortisol levels may “strongly predict cardiovascular death” in men and women both with and without pre-existing cardiovascular disease. In fact, this may help explain “death from a broken heart,” the heightened heart attack and stroke risk in the immediate weeks following the loss of a spouse. Higher cortisol levels days, months, or even years after losing someone you love may increase cardiac risk and reduce immune function. And, the rise in stress hormone levels from the loss of a spouse, a bump of about 50 points, is less than the bump you get by eating high-meat diet.

Cortisol may also help explain why those who are depressed tend to put on abdominal fat. The reason obesity around the middle is associated with elevated cortisol secretion may be that abdominal fat kind of sucks it up, so the accumulation of fat around our internal organs may be an adaptation by which our body deals with excess stress.

These spikes in stress hormone levels every time we eat a lot of meat may not just affect our health, but that of our children, which I discuss in my video Maternal Diet May Affect Stress Responses in Children. “Substantial evidence now suggests that maternal diets of high protein density have adverse effects on the fetus.” For example, back in the 1960s, an experiment was performed on pregnant women in Motherwell, Scotland, in which they were told to eat a high-meat diet in hopes of preventing preeclampsia, a disease of pregnancy. It didn’t work. In fact, the lowest preeclampsia rates I’ve ever seen were among women eating strictly plant-based diets—only 1 case out of 775 pregnancies. Preeclampsia normally strikes about 5 percent of pregnancies, so there should have been dozens of cases, suggesting a plant-based diet could alleviate most, if not all, of the signs and symptoms of this potentially serious condition. So what did happen when pregnant women went from eating about one daily portion of meat to about two portions a day? Mothers who ate more meat and fewer vegetables during pregnancy gave birth to children who grew up to have higher blood pressures.

“One explanation proposed for the adverse effects of high-meat/fish consumption is that this may increase maternal cortisol concentrations, which, in turn, affect the developing fetus,” resetting his or her stress hormone thermostat to a higher level. But, we don’t know until we put it to the test. And indeed, researchers found higher blood cortisol levels “in both the sons and daughters of women who had reported higher meat/fish” consumption, about a 5 percent increase for every meat serving per day. Such diets may present a metabolic stress to the mother and kind of reprogram the adrenal axis of their children, leading to lifelong hypercortisolemia, elevated levels of stress hormones in the blood. This may help explain why every daily portion of meat during late pregnancy may lead to a 1 percent greater fat mass in their children by the time they reach adolescence. So, this could increase the risk of their children becoming obese later in life and thus has “important implications for public health and in terms of prevention of obesity.”

What if they’re already born? We may be able to bring down children’s stress hormone levels with similar dietary changes, but this is just baseline stress hormone levels. Do children of mothers who eat more meat during pregnancy also have exaggerated responses to life stressors? Researchers put them through a stressful challenge—public speaking and mental arithmetic—and then measured their cortisol responses. If their mom ate less than two servings of meat/fish a day while she was carrying them, they got little shots of stress hormones from their adrenal glands. Those whose moms ate more really got stressed out, and those whose moms ate the most—17 or more servings a week, which is more than 2 servings each day—appeared to be really quaking in their boots. In a way, you are what your mother ate.


Want more craziness from Men’s Health magazine? Check out my video Changing a Man’s Diet After a Prostate Cancer Diagnosis.

Here are some other popular videos about eating healthfully during pregnancy:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

The Benefits of Vinegar Beyond Weight Loss

A double-blind, placebo-controlled, randomized study found that body weight and belly fat were significantly reduced by adding just a single tablespoon of vinegar to one’s daily diet. Is there any benefit to vinegar consumption if you’re not overweight? Well, the subjects’ triglycerides normalized, and, for those taking the larger dose of two tablespoons per day, there was a dip in blood pressure. Those effects may have just been because of the weight loss, though. Other than taste, is there any benefit to normal-weight individuals sprinkling vinegar on their salads? What about vinegar for controlling blood sugar? That’s the topic of my video Can Vinegar Help with Blood Sugar Control?.

If you feed people a half cup of table sugar, as their blood sugars spike, their artery function can become impaired. The higher the blood sugars go, the more the arteries take a hit. There’s a drug, though, that can block sugar absorption. By blunting the blood sugar spike with this drug, you can prevent the arterial dysfunction. This demonstrates that it’s probably good for your heart if you don’t have big blood sugar spikes after meals. In fact, how high your blood sugars spike after a meal is a predictor for cardiovascular mortality. So do people who eat lots of high glycemic foods, like sugary foods and refined grains, tend to have more heart attacks and strokes? Yes. They also appear more likely to get diabetes—but maybe people who eat lots of Frosted Flakes and Wonder Bread have other bad dietary habits as well?

The diets that have been put to the test in randomized controlled trials and proven to prevent diabetes are the ones focusing on cutting down on saturated fat and ramping up the consumption of fiber-rich whole plant foods, such as fruits, vegetables, and whole grains, without specific regard to lower or higher glycemic loads. The drug has been put to the test, though, and blunting one’s mealtime blood sugar spikes does seem to reduce the risk of developing diabetes, as well as reduce the risk of heart attacks and high blood pressure. So is there any way to prevent these blood sugar spikes without having to take drugs? Well, one way would be to not sit down to a half cup of sugar!

Yes, the drug can slow the progression of your atherosclerosis. You can see in my video Can Vinegar Help with Blood Sugar Control? how the arteries going to your brain narrow somewhat more slowly with the drug than without it. But wouldn’t it be better to eat a diet that actually reverses heart disease and diabetes? The healthiest diet to prevent the meal-related blood sugar and fat spikes—the oxidation and inflammation—is a diet centered around whole plant foods. But what if you really want a bagel? Instead of spreading drugs on it, spreading on some almond butter may help blunt the blood sugar spike from refined carbs. Another option is to dip your baguette in some balsamic vinegar.

“The consumption of vinegar with meals was used as a home remedy for diabetes before the advent of pharmacologic glucose-lowering therapy”—that is, before drugs came along—but it wasn’t put to the test until 1988. After all, how much money can be made from vinegar? Well, according to The Vinegar Institute, millions of dollars can be made! But a single diabetes drug, like Rezulin, can pull in billions—that is, until it was pulled from the market for killing too many people by shutting down their livers. The drug company still made out like a bandit, though, having to pay out less than a billion to the grieving families for covering up the danger.

There’s no liver failure from schmearing peanut butter on a bagel, though, and it cuts the blood sugar response in half. Similarly, drinking four teaspoons of apple cider vinegar diluted in water gives the same blunting of the spike—with the additional advantage over the peanut butter of lowering insulin levels in the blood. This is something peanut butter apparently can’t do. But putting peanut butter on your bagel is presumably better than having a bagel with lox because fish causes triple the insulin response. Red wine also increases insulin levels, though not as much as fish does, and also shoots up triglycerides. Non-alcoholic red wine, however, doesn’t cause the same problem.

What about vinegar? Not only may a tablespoon a day tend to improve cholesterol and triglycerides over time, vinegar can drop triglycerides within an hour of a meal, as well as decrease blood sugars and the insulin spike, potentially offering the best of all worlds.


Was that bursting with information or what? It’s because of everyone’s kind support that I was able to hire more than a dozen researchers to help me plow through the literature. I’m extremely grateful so many of you were able to see the potential and help NutritionFacts.org become what it is today. Onward and upward!

What’s that about belly fat being reduced? Check out other videos in my series on vinegar:

Did I say reverse diabetes? Reverse heart disease? For examples, see:

Sharing information that can help people prevent and reverse common diseases is my life’s work. Check out the full story in my series of introductory videos.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

 

Vinegar Is Good for You

Vinegar has evidently been used as a weight-loss aid for nearly 200 years. Like hot sauce, it can be a nearly calorie-free way to flavor foods, and all sorts of delicious exotic vinegars—like fig, peach, and pomegranate—are available to choose from. The question, though, is whether there is something special about vinegar that helps with weight loss, which is the topic of my video Does Apple Cider Vinegar Help with Weight Loss?.

Vinegar is defined as simply a dilute solution of acetic acid, which takes energy for our body to metabolize, activating an enzyme called AMPK that is like our body’s fuel gauge. If it senses that we’re low, it amps up energy production and tells the body to stop storing fat and start burning fat. And, so, given our obesity epidemic, “it is crucial that oral compounds with high bioavailability are developed to safely induce chronic AMPK activation,” which would be potentially beneficial for long-term weight loss. There’s no need to develop such a compound, though, if you can buy it in any grocery store.

We know vinegar can activate AMPK in human cells, but is the dose one might get when sprinkling it on a salad enough? If you take endothelial cells (the cells lining our blood vessels) from umbilical cords after babies are born and expose them to various levels of acetate, which is what the acetic acid in vinegar turns into in our stomach, it appears to take a concentration of at least 100 to really get a significant boost in AMPK. So, how much acetate do you get in your bloodstream sprinkling about a tablespoon of vinegar on your salad? You do hit 100, but only for about 15 minutes, and even at that concentration, 10 or 20 minutes exposure doesn’t seem to do much. Now granted, this is determined in a petri dish. What do clinical studies show us?

A double-blind trial was conducted investigating the effects of vinegar intake on the reduction of body fat in overweight men and women. The researchers call them obese, but they were actually slimmer than the average American. In Japan, they call anything over a BMI of 25 obese, whereas the BMI of the average American adult is about 28.6. Nevertheless, they took about 150 overweight individuals and randomly split them into one of three groups: a high-dose vinegar group drinking a beverage containing two tablespoons of apple cider vinegar a day, a low-dose group drinking a beverage containing only one tablespoon of apple cider vinegar a day, and a placebo control group drinking an acidic beverage they developed to taste the same as the vinegar drink but using a different kind of acid so, there was no acetic acid.

There were no other changes in their diet or exercise. In fact, the researchers monitored their diets and gave them all pedometers so they could make sure the only significant difference amongst the three groups was the amount of vinegar they were getting every day. Within just one month, there were statistically significant drops in weight in both vinegar groups compared with placebo, with the high-dose group doing better than the low-dose group, and the weight loss just got better month after month. In fact, by month three, the do-nothing placebo group actually gained weight, as overweight people tend to do, whereas the vinegar groups significantly dropped their weight. Was the weight loss actually significant or just statistically significant? Compared with the placebo group, the two-tablespoons-of-vinegar-a-day group dropped five pounds by the end of the 12 weeks. That may not sound like a lot, but they got that for just pennies a day without removing anything from their diet.

They also got slimmer, losing up to nearly an inch off their waist, suggesting they were losing abdominal fat. The researchers went the extra mile and put it to the test. They put the research subjects through abdominal CT scans to actually measure directly the amount of fat in their bodies before and after. They measured the amount of superficial fat, visceral fat, and total body fat. Superficial fat is the fat under your skin that makes for flabby arms and contributes to cellulite. Visceral fat, on the other hand, is the killer. It’s the fat that builds up around your internal organs that bulges out the belly—and the kind of fat the placebo group was putting on when they were gaining weight. Both the low-dose and high-dose vinegar groups, however, were able to remove about a square inch of visceral fat off that CT scan slice.

Like any weight loss strategy, it only works if you do it. A month after they stopped the vinegar, the weight crept right back, but that’s just additional evidence that the vinegar was working. But how was it working?

A group of researchers in the United Kingdom suggested an explanation: Vinegar beverages are gross. They created vinegar beverages that were so unpleasant the study subjects actually felt nauseated after drinking them and ate less of the meal the researchers provided. So, there you go: Maybe vinegar helps with both appetite control and food intake, though these effects are largely due to the fruity vinegar concoctions invoking feelings of nausea. Is that what was going on in the original study? Were the vinegar groups just eating less? No, the vinegar groups were eating about the same compared with placebo. Same diet, more weight loss––thanks, perhaps, to the acetic acid’s impact on AMPK.

Now, the CT scans make this a very expensive study, so I was not surprised it was funded by a company that sells vinegars, which is good, since we otherwise wouldn’t have these amazing data, but is also bad because it always leaves you wondering whether the funding source somehow manipulated the results. The nice thing about companies funding studies about healthy foods, though, whether it’s some kiwifruit company or the National Watermelon Promotion Board (check out watermelon.org), is, really, what’s the worst that can happen? Here, for example, even if the findings turned out to be bogus and worst comes to worst, your salad would just be tastier.


I’m so excited to finally be getting to this topic. Type “vinegar” into PubMed, the search engine biomedical literature, and 40,000 studies pop up. It took me a while to take it all in, but I’m so glad I did, as it’s something that has caused a shift in my own diet. I now try to add various vinegars every day.

This is the first of a five-part video series. See the other installments:

For more holistic approaches to weight loss, see:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: