Cutting back up to 25 percent of your calories per day helps slow your metabolism and reduce free radicals that cause cell damage and aging.

But would you want to?

You May Live Longer By Severely Restricting Calories, Scientists Say

Research has shown that sharp reductions in the amount of food consumed can help fish, rats and monkeys live longer. But there have been very few studies in humans.

Now, some researchers have found that when people severely cut calories, they can slow their metabolism and possibly the aging process. Clinical physiologist Leanne Redman, who headed the study at Pennington Biomedical Research Center in Baton Rouge, says the first challenge was finding people willing to take part. After all, they would have to cut their typical plate for breakfast, lunch and dinner by up to 25 percent. And, she says, none of them were overweight.

Ultimately, she recruited 53 healthy volunteers. One-third ate their regular meals. The rest were on the severe calorie reduction plan for two years. "I don't know if you understand the rigor of what it means to do calorie restriction every day," she says, but the volunteers were committed.

Not surprisingly, the people cutting calories lost quite a bit of weight — on average, 25 pounds. Those in the control group gained as much as 4 pounds. But weight loss was not the point. Redman wanted to know whether this dramatic reduction in calories could affect how quickly people age.

For testing, participants spent 24 hours in special rooms that measured their metabolic rates via gas, oxygen and carbon dioxide and how it changed over time. Redman noticed that for those on the restricted diet, their metabolism slowed and became more efficient. "Basically it just means that cells are needing less oxygen in order to generate the energy the body needs to survive; and so the body and the cells are becoming more energy efficient," Redman explains. And if less oxygen is needed to burn energy, then dangerous byproducts of that burning–free radicals–can be reduced.

"Oxygen can actually be damaging to tissues and cells, and so if the cells have become more efficient, then they've got less oxygen left over that can cause this damage,"she says. And that damage can accelerate aging. The study was published in the journal Cell Metabolism last month.

Now, these findings don't directly prove that drastic calorie-cutting will actually help people live longer. People would have to be followed for their lifetimes to prove that. But the study did find that blood pressure, cholesterol and triglycerides were lower in the group on severe calorie restriction. When those numbers are high, they can lead to life-shortening diseases.

The challenge is, most people may not be able to do a severe calorie-restricted diet, or even want to do it. Lowering metabolism can cause other problems. Biochemist Valter Longo, who studies longevity at the University of Southern California, says severely restricting calories for a time can mean you're more likely to gain weight in the end. "Basically, you have to eat progressively less to maintain the same weight."

Most Americans struggle with carrying around too much weight, which can cause countless health problems. "For most people, if you consider 70 percent of Americans are either overweight or obese, then you can see how, for most people, this would be a big problem," Longo says. It could lead to more "yo-yo dieting," where people who go off the diet eat more and return to their previous weight or even gain more weight. He is also concerned about the potential for muscle loss and a weakened immune system in those on severe calorie-restricted diets.

Instead of chronic calorie restriction, Longo is a proponent of mini-fasts. These are short reductions in calories to just 900 a day for five days a month, which he says have the benefits of fasting without the potentially negative long-term effects. In fact, he wrote the book on it: The Longevity Diet. Longo stresses the importance of eating more fruits and vegetables and less meat. It may not ultimately lengthen your life, he says, but it can certainly help you maintain a healthy weight and avoid the kinds of chronic illnesses that can shorten it.

These practices are not for everyone. If you have a history of eating disorders check with your doctor before starting any new regimen.

Mediterranean diet boosts beneficial bacteria, study finds

Here's another reason to eat a Mediterranean-type diet: It's good for your gut.

Scientists at Wake Forest Baptist Medical Center found that eating a plant-based diet enhanced the good bacteria living in the gut by up to 7 percent as compared to only 0.5 percent from eating a more meat-centric, Western diet. Using an animal model, the research team designed the study to mimic human Western- and Mediterranean-type diets that could be controlled and analyzed over a sustained period of time. Long-term diet studies involving people usually rely on self-reported dietary intake collected via questionnaires with nutrient intake only estimated, said the study's lead author Hariom Yadav, Ph.D., assistant professor of molecular medicine and microbiology and immunology at Wake Forest Baptist. The study findings are published in the April 25 online edition of the journal Frontiers in Nutrition.

In the pre-clinical study, non-human primates were randomized to either Western or Mediterranean diet groups and studied for 30 months. The Western diet consisted of lard, beef tallow, butter, eggs, cholesterol, high-fructose corn syrup and sucrose, while the Mediterranean diet consisted of fish oil, olive oil, fish meal, butter, eggs, black and garbanzo bean flour, wheat flour, vegetable juice, fruit puree and sucrose. The diets had the same number of calories.

At the end of the 30 months, Yadav's team analyzed the gut microbiome – the good and bad bacteria that live in the gastrointestinal tract – in both diet groups through fecal samples. They found the gut bacteria diversity in the Mediterranean diet group was significantly higher than in the group that ate the Western diet. "We have about 2 billion good and bad bacteria living in our gut," Yadav said. "If the bacteria are of a certain type and not properly balanced, our health can suffer. "Our study showed that the good bacteria, primarily Lactobacillus, most of which are probiotic, were significantly increased in the Mediterranean diet group."

The data revealed in this study should be useful for further studies aimed at understanding the diet-microbiome-health interactions in humans, including obesity, type 2 diabetes, cardiovascular disease and psychiatric disorders, Yadav said.

Why zero-calorie sweeteners can still lead to diabetes, obesity

Common artificial sweeteners shown to change how the body processes fat and energy.

Increased awareness of the health consequences of eating too much sugar has fueled a dramatic uptick in the consumption of zero-calorie artificial sweeteners in recent decades. However, new research finds sugar replacements can also cause health changes that are linked with diabetes and obesity, suggesting that switching from regular to diet soda may be a case of 'out of the frying pan, into the fire.' Artificial sweeteners are one of the most common food additives worldwide, frequently consumed in diet and zero-calorie sodas and other products. While some previous studies have linked artificial sweeteners with negative health consequences, earlier research has been mixed and raised questions about potential bias related to study sponsorship.

This new study is the largest examination to date that tracks biochemical changes in the body -- using an approach known as unbiased high-throughput metabolomics -- after consumption of sugar or sugar substitutes. Researchers also looked at impacts on vascular health by studying how the substances affect the lining of blood vessels. The studies were conducted in rats and cell cultures.

"Despite the addition of these non-caloric artificial sweeteners to our everyday diets, there has still been a drastic rise in obesity and diabetes," said lead researcher Brian Hoffmann, PhD, assistant professor in the department of biomedical engineering at the Medical College of Wisconsin and Marquette University. "In our studies, both sugar and artificial sweeteners seem to exhibit negative effects linked to obesity and diabetes, albeit through very different mechanisms from each other." Hoffmann presented the research at the American Physiological Society annual meeting during the 2018 Experimental Biology meeting, held April 21-25 in San Diego.

The team fed different groups of rats diets high in glucose or fructose (kinds of sugar), or aspartame or acesulfame potassium (common zero-calorie artificial sweeteners). After three weeks, the researchers saw significant differences in the concentrations of biochemicals, fats and amino acids in blood samples. The results suggest artificial sweeteners change how the body processes fat and gets its energy. In addition, they found acesulfame potassium seemed to accumulate in the blood, with higher concentrations having a more harmful effect on the cells that line blood vessels. "We observed that in moderation, your body has the machinery to handle sugar; it is when the system is overloaded over a long period of time that this machinery breaks down," Hoffmann said. "We also observed that replacing these sugars with non-caloric artificial sweeteners leads to negative changes in fat and energy metabolism."

So, which is worse, sugar or artificial sweeteners? Researchers cautioned that the results do not provide a clear answer and the question warrants further study. It is well known that high dietary sugar is linked to negative health outcomes and the study suggests artificial sweeteners do, too. "It is not as simple as 'stop using artificial sweeteners' being the key to solving overall health outcomes related to diabetes and obesity," Hoffmann added. "If you chronically consume these foreign substances (as with sugar) the risk of negative health outcomes increases. As with other dietary components, I like to tell people moderation is the key if one finds it hard to completely cut something out of their diet."

Weekly meal prep: Mastered.

Here's how to have healthy food ready when you need it. By John Berardi, Ph.D.

Check out these time-saving weekly meal prep strategies, used by Precision Nutrition’s most successful clients. And learn how they can help you prioritize healthy eating too.

Most people know what a healthy, balanced meal looks like. The real question they have is: How do you consistently eat healthy, balanced meals in the context of real life? You know, like “I got home late, after a long meeting, then my toddler spilled an entire bottle of olive oil on the kitchen floor!” (Yeah, true story).

With the following meal prep strategies, we teach our clients exactly how to have healthy food ready when they need it. The result? A fridge full of fast, healthy options to choose from, even as life continues to unfold.

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