Chapter 181
Eat More, Fewer Calories
One might assume that immunosuppression during undernutrition arises from the release of steroid stress hormones, yet although total fasting drives cortisol levels up dramatically—they can double in five days—this does not occur with less stringent caloric restriction. Although many indicators of immune function improve during caloric restriction, that does not necessarily translate into a higher survival rate from infections. Despite an apparent rejuvenation of immune system values, in rodents reducing food intake by 20 to 40 percent compared to the ad libitum amount had negative effects on fighting bacterial, viral, fungal, or parasitic infections. When mice that had been on a calorie-reduced diet were put back on a full diet two weeks before being infected with influenza, their survival rate improved to the level of normally fed mice. Researchers recommend that people without clairvoyant abilities not restrict calorie intake before, or perhaps throughout, the entire flu season.
A consistent benefit of restricted calorie intake is that blood pressure improves after just one to two weeks. Unfortunately, it can also work a bit too well and cause orthostatic intolerance, which shows up as dizziness or lightheadedness when standing up and, in severe cases, can lead to fainting. Drinking enough helps.
What about loss of muscle mass? Contrary to what one might expect, restricted calorie intake delays age-related muscle loss in rats and monkeys. Details can be found at see.nf/restrictionpitfalls, but participants in the CALERIE study generally got stronger. Aerobic capacity also increased slightly in the calorie-restriction group compared to the control group. Higher protein intake is often recommended to preserve more lean mass, but most studies find no positive effect on preserving muscle strength and function, whether young or old, active or inactive, and high protein intake during weight loss has “profound” negative effects on metabolism because it undermines the benefit of weight loss on insulin sensitivity. If you lose ten kilos, the body can regulate blood sugar much better than in a control group that did not lose weight. But if you lose the same amount while eating a high-protein diet (an additional 30 grams of protein per day), for blood sugar it is as if you had not lost any weight at all.
You can, of course, put muscle back on afterward, but the best way to preserve muscle mass even during weight loss is exercise. Resistance training just three times per week prevents over 90 percent of lean-mass loss during caloric restriction. The same presumably applies to loss of bone mass. If you lose weight only by restricting calorie intake, bone density decreases at fracture-prone sites, such as the hip and spine. In any case, in the same study, no bone loss was found in randomized participants who lost weight with exercise. You can never argue against the call for more movement, but even without exercise, the “very small” decline in bone density in the CALERIE study increased the ten-year risk of osteoporotic bone fractures by only about 0.2 percent. A high-resolution MRI study of the bones of CRONies found a reduction in bone mass but not in bone strength. The tiny honeycomb structure of the bones appeared to have been preserved despite the decline in bone mass.
Will pollutants be released?
It is believed that body fat plays a protective role by binding toxins such as PCBs and DDT, which are then released during weight loss. This is one reason health authorities advise breastfeeding women not to try to lose weight. How you can protect your vital organs, I show in see.nf/fastingdetox. It does not help to snack on Pringles made with the synthetic fat substitute olestra, but fiber can bind these pollutants and flush them out of the body. In see.nf/eatlow you can learn how to prevent industrial toxins from accumulating in the first place.
Eat More, Fewer Calories
The result of the CALERIE study is that the benefits of moderately calorie-restricted eating—improvement in blood pressure, cholesterol, mood, libido, and sleep—far outweigh the risks. The fact that calorie restriction seems to have such broadly positive effects prompted a commentary in the trade journal of the American Medical Association, which stated: “The results of this well-designed study suggest that the consumption of excess calories is a burden not only for physical homeostasis, but also for psychological well-being.” This is all the more remarkable when you consider how little calorie intake was actually restricted.
At the end of the 24-month CALERIE study, the low-calorie group was consuming only 100 calories per day less than the ad libitum control group—a waning of dietary discipline, since at the end of the first year they had still been eating 200 calories per day less. The old refrain is that you can get all that simply by skipping the daily caffè latte or eating only half the muffin du jour, but if you reach for healthier foods, you get the same calorie reduction while eating more, not less.
Among vegans, only 2 to 3 percent are obese, presumably because people who eat plant-based consume up to 464 fewer calories per day even though they eat the same amount—or even more. That is the beauty of low-calorie-density foods: more food, less weight. In How Not to Diet I discuss the topic of calorie density in detail.
The founding director of Harvard’s Center for Research on Aging, David Sinclair, wrote: “If after 25 years of aging research and after reading thousands of scientific studies I can make one recommendation about what to do to live as long as possible, a sure-fire way to stay healthier longer, then this: Eat less.” However, eating fewer calories does not necessarily have to mean smaller portions. For example, the longevity of people in Okinawa was due in part to the fact that they ate only about 1800 calories per day. But because plants are so low in calories, they actually consumed more food.
Intermittent Fasting
Instead of saving calories day in, day out, how about eating as much as you want every other day instead? Or only for a few hours each day? Or how about fasting two days per week or five days per month? Those are all examples of intermittent fasting, and perhaps this is even the way of eating we were made for. For millennia, our ancestors probably ate only one large meal on a given day, or had to go for days without any food at all.
Could it be that intermittent fasting stresses our bodies in a positive way, similar to exercise, through hormesis? Mark Twain was convinced: “A little starvation can really do more for the average sick person than the best medicine and the best doctors. I do not mean restricted eating; I mean complete abstinence from food, for a day or two.” But Twain also said: “Many a small thing has been made large by the right kind of advertising.” Is the fuss about intermittent fasting just hype?
I discuss all the major studies on alternate-day fasting (“alternating fasting”) in insee.nf/altdayfasting, and studies on the 5:2 diet (eating five days each week) in see.nf/52fmd. Bottom line: intermittent fasting does not appear to be any more beneficial than sustained daily restriction. And as I report in see.nf/altdaysafety, the largest and longest alternate-day fasting study found a disturbingly significant increase in LDL cholesterol. In addition, a study of postmenopausal women found that intermittent calorie restriction led to twice as much lean-mass loss as sustained restriction. And I warn diabetics and people taking medications against intermittent fasting, although concerns about mood, cognition, and eating disorders have diminished. Symptoms such as irritability and difficulty concentrating on fasting days can decrease over time. And of eleven intervention studies, four showed an increase in binge-eating episodes, two no change, and the other five a decrease.