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Then & Now: Calorie Restriction and the Impact on Disease

Posted by Dr. Barry Sears

Feb 1, 2017 8:26:24 AM
Dr. Sears' Blog:

 

Reduce your risk of chronic disease by making simple changes to your diet. Starting with Hippocrates 2,500 years ago, to Luigi Carnaro 400 years ago, to Dr. Barry Sears today, data continues to prove that a calorie restricted diet can reduce your risk of chronic disease. Discover how you can benefit from history repeating itself.

 

More than 400 years ago, Luigi Cornaro demonstrated that calorie restriction increases your health span. The story began in the year 1507, when Cornaro, a Venetian nobleman, was near death at age 40 due to a poor dietary lifestyle. At that point, he started a rigorous calorie-restriction program. Starting at age 83, Cornaro wrote three widely-read diet books. When Cornaro died at age 99, his death was due simply to old age, not from any chronic disease.

 

Calorie Restriction is Not Malnutrition

Calorie restriction is not the same as starvation. It usually consists of a 30% reduction in normal caloric intake without sacrificing any nutrition. A recent study set out to validate the impact of calorie restriction on species closest to humans.1 The researchers used rhesus monkeys which share 93% of the same genes as us and live for about 30 years. So essentially you can assume these findings from monkeys should be applicable to humans. Virtually all the earlier work on calorie restriction had been done in worms and mice which are not quite the same as humans in terms of genes or lifetime.

 

What was impressive about this study, was that it was a 30-year experiment to determine the long-term consequences of caloric restriction versus normal intake. When the calorie restriction was started after the monkeys had reached maturity, they didn’t live that much longer than those fed a normal diet. They did however have significantly lower levels of cancer, heart disease, and insulin resistance than controls consuming a normal laboratory diet. The authors state that there are clear parallels between humans and rhesus monkeys and that it is quite probable that the healthy effects of calorie restriction seen in monkeys will also be visible in humans.

 

The Advantages of a Calorie-Restricted Diet

To understand the real advantage of a calorie-restricted diet requires an understanding of the link between diet and inflammation. A calorie-restricted diet is also an anti-inflammatory diet. This means that chronic diseases with a strong inflammatory linkage such as obesity, diabetes, Alzheimer’s, heart disease, and cancer to name just a few, can either be prevented or significantly managed following such an eating plan.

 

One would think following an anti-inflammatory diet should be the goal of health care reform. This could be our answer to continually rising healthcare costs, especially since the majority of those costs come when we are plagued chronic disease in our last years of life? Today health care “reform” generally increases the size of your deductible before your health insurance actually kicks in. The best strategy to overcome such “reform” is simply to not to get sick in the first place. That is the promise of calorie restriction. The proof it works was demonstrated in the above mentioned 30-year rhesus monkey study.

 

Of course, calorie restriction in free living humans is only possible if you are never hungry or fatigued. The Zone Diet was built upon this concept. That makes the Zone Diet a lifelong dietary program to treat heart disease and diabetes by reducing inflammation. The caloric ratio of the macronutrients (carbohydrates to protein to fat) is approximately 40–30–30. This balance allows for stabilization of blood sugar to prevent hunger and fatigue.

 

The Zone is also nutritionally superior (if not greatly exceeding standard diet) if the carbohydrates consumed are primarily non-starchy vegetables. These will be exceptionally rich in essential nutrients including polyphenols and fermentable fiber (i.e., prebiotics) necessary for gut health.

 

If you take the 30% calorie restriction in the rhesus monkey study and applied it to humans, that would mean an average adult male would consume 1,500 calories per day and an average female 1,200 calories per day. It doesn’t sound like a lot a calories, but without the correct balance of macronutrients, those decreased calorie levels would likely generate constant hunger and fatigue.

 

Obviously, this would make it difficult to live the rest of your life regardless of the health benefits. I put forward the balance of macronutrients necessary for controlling hunger and fatigue in my first book, The Zone.2 A decade later, those same recommendations were the foundation of the new dietary guidelines of the Joslin Diabetes Center at Harvard Medical School for treating obesity and diabetes.3 This year, Joslin published their 5-year study on diabetic patients following such a dietary program.4 The results were exceptionally encouraging for all diabetics. And if they are good for diabetics, then they will be extraordinary for non-diabetics.

 

How to Combat Hunger on a Calorie Restricted Eating Plan

Your first thought might be: How can I comply with this monkey food business, I’ll surely die. I guarantee you that the monkeys didn’t die following a calorie-restricted diet and neither will you. How? First, the carbohydrate intake on the Zone Diet is limited to about 40% of total calories. This ensures that the brain gets its daily need for glucose, which is about 130 grams of glucose.

The Zone Diet contains 100 to 150 grams of carbohydrates (400 to 600 calories), split over three meals and one or two snacks, which easily supplies that level of glucose for optimal brain function. However, if these carbohydrates were mostly composed of non-starchy vegetables then to consume 400 to 600 calories of carbohydrates would require you to eat approximately 4 pounds per day. Although this represents only about 50 – 67% of the total amount of carbohydrates in our typical American diet, you can see it may be difficult to consume the required amounts for the Zone Diet because of the very low glycemic index of the carbohydrates.

 

Furthermore, you never want to consume more than 30 to 40 grams of carbohydrates at any one meal. Any greater amount is going to generate excess insulin, which makes you hungry and fatigued by driving down blood glucose levels. The result is you are constantly hungry, searching for food all the time.

 

The secret of the Zone Diet is that the glycemic load of a meal is balanced by adequate levels of low-fat protein (25-30 grams) at each meal to help stabilize blood sugar levels and to release satiety hormones (like PYY and GLP-1) from the gut to tell the brain to stop eating.

 

The Zone Paradox: Fewer Calories Doesn’t Equate to Hunger or Fatigue

Although the Zone Diet is a calorie-restricted diet, you will not be hungry or fatigued. This is the Zone Paradox. It is untrue that the Zone Diet is a high protein diet. Yet, following the Zone Diet guidelines you still get the absolute protein intake of the typical American diet because even though the percentage of protein (30% of total calories) is higher, the total number of calories being consumed daily is restricted. Because of its calorie restriction, it is also a low fat diet in absolute terms. Finally since you always consume more carbohydrates than protein, it is difficult to refer to the Zone Diet as a high-protein, low-carbohydrate diet. It’s simply not correct since you are always consuming more carbohydrates than protein at a meal. Thus, the best description of the Zone Diet it is a calorie-restricted, protein-adequate, carbohydrate-moderate, and low fat dietary plan. Who could argue with that? Obviously not the Joslin Diabetes Center at Harvard.

 

As Hippocrates said 2,500 years ago, “Let food be your medicine and medicine your food.” Luigi Cornaro demonstrated it works 400 years ago, and today the Zone Diet makes it possible to live better with the least amount of effort if you are willing to balance your meals to live a life without hunger or fatigue.

 

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References:

  1. Mattison JA et al. “Caloric restriction improves health and survival of rhesus monkeys.” Nat Comm 8:1-12 (2017).
  2. Sears B. The Zone. Regan Books. New York, NY (1995).
  3. Giusti J and Pizzotto J-A. “Interpreting the Joslin Diabetes Center and Joslin Clinic clinical and nutrition guidelines for overweight and obese adults with type 2 diabetes.” Curr Dia Rep 6:405-408 (2005).
  4. Hamdy O et al. “Long-term effect of intensive lifestyle intervention on cardiovascular risk factor in patients with diabetes in real-world practice: a 5-year longitudinal study.” BMJ Open Dia Res Care 5:e000259 (2017).

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