For many people, the New Year is a time to adopt new habits as a renewed commitment to personal health.
Newly enthusiastic fitness buffs pack into gyms and grocery stores are filled with shoppers eager to try out new diets.
But, does scientific evidence support the claims made for these diets?
In a new review study, researchers conclude that intermittent fasting does.
The research was conducted by a team at Johns Hopkins University.
The team intended to help clarify the science and clinical applications of intermittent fasting in ways that may help physicians guide patients who want to try it.
Intermittent fasting diets fall generally into two categories: daily time-restricted feeding, which narrows eating times to 6–8 hours per day, and so-called 5:2 intermittent fasting, in which people limit themselves to one moderate-sized meal two days each week.
Many animal and some human studies have shown that alternating between times of fasting and eating support cellular health, probably by triggering an age-old adaptation to periods of food scarcity called metabolic switching.
Such a switch occurs when cells use up their stores of rapidly accessible, sugar-based fuel, and begin converting fat into energy in a slower metabolic process.
Previous studies have shown that this switch improves blood sugar regulation, increases resistance to stress and suppresses inflammation.
Because most Americans eat three meals plus snacks each day, they do not experience the switch or the suggested benefits.
In the study, the team notes that four studies in both animals and people found intermittent fasting also decreased blood pressure, blood lipid levels and resting heart rates.
Evidence is also mounting that intermittent fasting can modify risk factors associated with obesity and diabetes.
Two studies of 100 overweight women showed that those on the 5:2 intermittent fasting diet lost the same amount of weight as women who restricted calories, but did better on measures of insulin sensitivity and reduced belly fat than those in the calorie-reduction group.
In addition, intermittent fasting could benefit brain health too.
A recent study found that 220 healthy, non-obese adults who maintained a calorie-restricted diet for two years showed signs of improved memory in a battery of cognitive tests.
While far more research needs to be done to prove any effects of intermittent fasting on learning and memory, if that proof is found, the fasting — or a pharmaceutical equivalent that mimics it — may offer interventions that can stave off neurodegeneration and dementia.
The lead author of the study is Johns Hopkins Medicine neuroscientist Mark Mattson, Ph.D.
The study is published in The New England Journal of Medicine.
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