By Brian Delaney and Lisa Walford, this book is an introduction to calorie restriction diet or CR diet as used for longevity.
It's a diet with a goal to reduce chances of suffering age-related diseases like cancer, heart-disease, or diabetes. It's flexible and emphasizes eating healthy, nutrient-rich foods while reducing empty calories.
Most people refer to it as "CR" for calorie restriction. It was made popular by Roy Walford, a gerontology researcher. Many researchers have examined subjects by reading biomarkers before/after starting CR. The average age improves for animals on CR diet. No long term studies on humans have been done (as it would be unethical and take too long), but short term studies have yielded great results on biomarkers.
The authors give examples of what daily meals are like for different individuals. Some are strict, some are relaxed. A typical day might be:
- tea in the morning, light soy-protein lunch, big salad with fruit for dinner
- whole-grain cereal with fruit in morning, skipped lunch, large salad dinner
- salad for breakfast, mixed fruit/nuts and tea for lunch and dinner
Authors recommend contacting the CR Society International or other experts if you have any questions about CR.
Research involving animals on CR diets have shown that it increases the maximum life span much more dramatically than exercise, antioxidants, and so on. There has also been indicators that youthful traits still exist in older ages such as maze runs and reproduction.
There has not been any human studies other than short-term ones which record biomarkers. Humans on CR diets tend to show significant changes in their biomarkers which are associated with less risk of heart disease, cancer, diabetes, cerebrovascular disease, and other age-related diseases.
Clive McCay accidentally discovered the longer term effects at Cornell University while studying stunted growth in mice. More recently, CR has been shown to improve insulin sensitivity. Insulin enables cells to use glucose, overtime our cells become less responsive to insulin which leads to high levels of glucose and diabetes. Glucose is like gas, too much can cause damage. We need just enough to keep our bodies running. CR improves insulin sensitivity by lowering the amount of glucose in our bodies.
CR has been shown to reduce the amount of DNA damage in our bodies and that telomere length seems to increase. There's also a reduction in oncogenes. Laboratory animals on extreme CR have a reduced decline in sexual activity with age. There have also been signs of lowered blood pressure and reduced risk of arthritis. The authors include references to each research paper.
There is a catch. Bodies tend to experience lower temperatures on CR diets. If you're already underweight, this is not a good diet for you. Reducing calories will result in losing weight.
Your body needs a certain amount of protein, lipids, vitamins, minerals, and calories. CR aims to get that nutrition while reducing caloric intake. Ratios are important.
Proteins are made up of amino acids. There are twenty kinds, eight of which are essential because the human body cannot synthesize it. In Western cultures, it's very easy to get the proteins you need. Some protein is better than other proteins because it has the essential eight amino acids (like egg).
Lipids are also known as fat. The ratio of fatty acids is important. The fat found in fish, nuts, and seeds are better to eat than the fats found in vegetable oils. Lipids include fatty acids, triglycerides, sterols, waxes, phospholipids, and lipoproteins. They're used to make cell walls and hormones. Every single lipid can be made by the body except for omega-3 and omega-6 fatty acids. You need to maintain a good balance of both. Omega-6 fatty acids tend to trigger issues like arthritis and high blood pressure. Omega-3 combats this. Western cultures tend to have foods high in omega-6. So eat more foods that contain omega-3.
Vitamins and minerals are micronutrients. They're not directly used in the body but act as supplements to help build other essential materials. You need a little bit of a lot of variety. Too much of any single vitamin or mineral will have harmful effects. You can get this by eating a variety of fruits and veggies (think a variety of colors).
Calories fuel your body and comes from carbohydrates, lipids, protein, and alcohol. For the CR diet, we're trying to reduce the amount of calories while making sure you get the necessary nutrition.
Some basic guidelines to follow:
- cooking plants break down cell walls making nutrients more accessible
- cooking too much can remove essential nutrients
- steaming veggies until they become soft is a good compromise, or try eating both raw and steamed veggies in one meal
- include as many unprocessed foods as practical (whole-grain instead of white bread, corn instead of corn chips)
- eat a variety of fruits and veggies
- don't eat a lot of meat, particularly fatty meat
- eat legumes and grains if you're a vegetarian
- get at least 20 minutes of aerobic exercise at least 3x week
This chapter covers the current theories of aging and how CR might effect it. The current recommended calories for moderately active men of average size is 2500/day. For women it's 2000/day.
Both aging and how CR affects it are all theories.
Disposable Soma - disposable body - this theory says individuals are disposable so long as the species can survive. On CR, you're tricking your body into thinking food is scarce. It begins to act differently in order to survive. For a species, if food is scarce it makes sense that individuals must remain youthful longer so that reproduction can occur at a later stage (thus waiting until food is more available).
Antagonistic Pleiotropy - some genes are beneficial to use early in our lives but antagonistic later on. IGF-1 helps us grow early but accelerates aging later. Cell senescence is required to prevent cancer but could cause use to grow older.
Rate of living - the faster you live the sooner you'll die. Humans on CR use their body's energy more efficiently.
Immunological - similar to antagonistic pleiotropy, some antibodies in your body attack parts of it. These tend to multiply with age. CR reduces the amount of this autoantibodies.
Neuroendocrine - network of brain cells, hormones, and glands govern the homeostasis of your body. Over time, the hypothalamus gets damaged and regulates hormone less effectively. Animals on CR tend to retain their youthful hormone regulation longer.
Cellular Senescence - most cells divide less than fifty times by the time we die due to the hayflick limit and perhaps telomeres. Animals on CR experience less telomere shortening during DNA replication.
Wear and Tear - the general theory that your system gets damaged overtime as we use it causing aging.
Glycemic - we have a lot of glucose floating in our system. Too much fuel causes collateral damage. Glucose molecules spontaneously binds to amino acids in proteins, changing its structure and functions becoming advanced glycation end-products (AGEs). CR lowers average levels of circulating glucose.
Free Radical - this theory says free radicals cause havoc in our systems because they steal electrons from molecules causing a domino effect.
It may not be worth giving up the pleasures of food to extend your youthful life. It's your decision. Keep in mind that there are no absolutes, you can still eat anything you want in moderation.
CR should not be attempted if you are pregnant, not fully grown, have a history of eating disorders, or have not consulted a health-care professional.
There are three ways to implement CR:
- weight watching
- calorie counting
- measuring health markers
For weight watching, you should have a set point which is the weight your body naturally wants to be at given no exercise and allowing yourself to eat whatever you want. Implementing CR should result in losing 10%-25% of that weight.
Calorie counting is just what it sounds like, keep a diary of the food you eat. First, stick with the same amount of calories but replace the food so it's healthier (more veggies and nutrient-rich). Then slowly reduce your calories.
You can mix and match what you eat as long as you get a variety of veggies and nutrient-rich foods. You can eat whenever you want, do whatever fits your schedule best. Don't reduce calories immediately, it needs to be a gradual change. Focus on veggies and fruits and think of it as a rainbow:
- blue - blueberries
- purple - red cabbage, black olives, grapes, plums, blackberries, eggplants
- red - beets, tomatoes, red peppers, red onions, apples, cherries, watermelon, strawberries, rasberries
- orange - carrots, melons, oranges, tangerines, peaches, apricots
- yellow - corn, bananas, lemons, grapefruit, pineapple
- green - cabbage, lettuce, bok choy, broccoli, sprouts, kale, spinach
- white - cauliflower, garlic
Plants will form the bulk of your diet. Aim for the good fats like monounsaturated fats instead of saturated fats. Fatty food should include more omega-3 like virgin olive oil and flaxseed oil.
Your priorities are:
- reduce intake of calories
- eat enough protein for body weight and level of CR
- get adequate amounts of omega-3 fatty acids
- eliminate processed foods from diet
You can do it in steps:
- eliminate all junk food and empty calories
- start introducing more veggies and fruits to your diet
- make sure you have all the nutrients required
- avoid sugars
Your food diary will include nutrient/caloric intake but will also have extra meanings/circumstances like what caused splurges. This way, you can keep track and get rid of the root cause.
The categories your food belongs to are:
- vegetables and fruits
- whole grains
- protein
- omega-3
- fats
- calcium
- enriched foods and sweets
- miscellaneous
This chapter includes a ton of examples from CR dieters. Here's an example day:
- walnuts, almonds, peanuts
- avocado slice, whole wheat toast, hummus spread
- apple/carrot juice
- steamed broccoli, red pepper, kale, tomato squash, sweet potato, onions, cauliflower, tomato juice, tofu
- toasted almonds, black tea
Here's another example day:
- smoothie with soymilk, yogurt, banana, strawberries
- almonds, tea
- broccoli, cauliflower, carrot, zucchini, spinach, mushrooms, celery, red pepper, tomato, purple cabbage, cucumber, olive oil, hummus, avocado, whole wheat toast
- lentils with spices, peas, carrots, and red wine
The steps to implement any lifestyle change are:
- believe in evidence
- cultivate that it will work for you
- make a plan
- trial-and-error implementation
- stay on board or revert back
This chapter just includes some tips on how to stick with CR. Some tips includes making a contract with yourself, setting a specific length trial period, and learning as much as possible about nutrition.
Eating treats is usually due to "triggers" and not hunger. For example, your kids are microwaving an aromatic pizza or everyone is getting some popcorn at the movie theaters. If hunger actually strikes, try snacking on fruit or veggies. Breaking the longevity diet is usually due to poor habits and not hunger. Recognize the poor behavior and fix it. The authors call this a warrior.
On the flip side, if the beginning of the book was interesting you're probably a health nut who wants to learn more about nutrition. The authors call this an explorer. Don't purchase and bring home anything you shouldn't eat.
After watching what you eat (less processed foods, more whole foods) the next step is to watch your weight. Perhaps once or twice a week.
It's the ratio of nutrients to calories that's important. It's about optimal nutrients with restricted calories. If you prefer foods with low energy density, your plate will be full with veggies, whole grains, and a little bit of protein. You could also have smaller portions with lots of proteins.
Some people fast, for instance one of the authors fast one day a week. This becomes her most productive day since she doesn't have to worry about food. It shaves off ~1000 calories off her weekly average.
Exercise adds life to your years but not years to your life. It can lower blood pressure, lower cholesterol, improve metabolism, improve bone density, and reduce stress. It improves the average life span but doesn't extend maximum life span (or at least there have been no studies that proved it yet). In fact, some studies have shown that exercise has no effect on the maximum life span.
Aerobics is good for the heart and brain. While it doesn't slow down the aging process, it does reduce the risks of getting many diseases. Aerobic fitness is about getting oxygen to your muscles. A strong heart is able to pump more oxygen-rich blood with each beat. Weaker hearts must beat faster and work harder.
Overdoing it will actually hurt your body, leading to damaged joints/bones. The authors recommend not going over 3 times a week with twenty minute sets.
Regular exercise reduces your resting metabolic rate. This is the minimum number of calories you need to eat while you are doing absolutely nothing. This accounts for 70% of the calories needed. The author recommends yoga.
Less stress leads the better health. The authors dedicate an entire section to this. Chronic stress decreases the body's ability to heal.
This chapter includes practitioners' stories about why they do CR and how it is different from other diets. CR doesn't have a set amount of rules, it's up to you to learn about nutrition and how to effectively pack in nutrients to a small amount of calories. It's also more of a lifestyle change for a more youthful/longer life instead of weight loss.
This chapter includes a few recipes.
Veggies Primavera:
- 1 pound packaged raw, cut, mixed veggies (150 calories)
- choose one of the following: fish, turkey leg, chicken breast, chickpeas, edamame, tofu for protein
- select a sauce: extra-virgin olive oil, balsamic vinegar with herbs
Pesto:
- fresh is better but commercial is easier
- 3 cloves garlic peeled
- 1 bunch of fresh basil or half/half basil/arugula
- 1 tablespoon olive oil
- 4 tablespoons parmesan cheese
Indian Masala Sauce:
- 1 tablespoon olive or coconut oil
- 2 cloves garlic minced
- 2 teaspoons grated fresh ginger
- 1 onion, minced
- 1 jalepeno or serrano chile
- 1/2 teaspoon ground cumin
- 1/2 teaspoon ground coriander
- 1/2 cup plain nonfat or soy yogurt
A huge chunk of the book is made up of recipes, but it's pretty easy to come up with your own as long as you know the basics of nutrition.