Study under review: A Randomized Pilot Study Comparing Zero-Calorie Alternate-Day Fasting to Daily Caloric Restriction in Adults with Obesity
The mythical 'optimal diet' has little to do with macronutrient, energy or vitamin content. Instead, the ideal diet is determined by what the dieter can, and will, actually stick to. This idea is supported by studies such as the A to Z weight loss study and the BBC weight loss study. Those studies focused on macronutrient content, type of diet, or food group elimination, and were generally in line with the current guidelines for treatment of obesity, which recommend a moderate daily caloric restriction (20-30% energy deficit below requirements for weight maintenance).
In most cases, consistent daily calorie reduction is typically able to produce moderate weight loss over time. However, intermittent calorie restriction is another option that may work well for some people. Intermittent fasting has been growing in popularity, and can be practiced in a number of different ways.
Among the most studied forms of fasting are alternate day fasting (ADF) and alternate day modified fasting, which involve either complete fasting or the consumption of only 25% of one's individual energy requirements, respectively. Multiple studies have shown that ADF may reduce the risk of diabetes and cardiovascular diseases. Time-restricted eating windows are another form of fasting, in which a person eats all of their food within a daily eating window of 8 to 12 hours. This method has been growing in popularity, though the most impressive research on time-restricted eating windows still exists mainly in animal models. A review comparing intermittent vs. daily calorie restriction concluded that, although they have similar effects on total bodyweight reduction, intermittent calorie restriction is more effective for retaining lean mass. Some people might also find it easier to adhere to intermittent compared to daily calorie restriction for short treatment durations (e.g. 12 weeks), due to its favorable effects on hunger and satiety hormones.
A number of studies over the past ten years have shown the beneficial effects of ADF, but randomized trials comparing ADF and daily calorie restriction are needed in order to show greater efficacy. Accordingly, the aim of this pilot study was to evaluate the safety and tolerability of an eight week ADF program and compare it with moderate daily caloric restriction in its effects on body weight, body composition, lipids, and insulin sensitivity. The study also aimed to assess risk for weight regain between groups after 24 weeks of unsupervised follow-up. To gain insight into potential mechanisms of action, changes in resting metabolic rate (RMR) were measured along with leptin and ghrelin, which are hormones involved in energy balance, and brain-derived neurotrophic factor (BDNF), which has been suggested to mediate fasting-induced improvements in cognitive function as well as playing a role in energy balance.
Alternate-day fasting (ADF) is a form of intermittent fasting where a person either fasts completely or limits food intake to approximately 25% of daily needs every other day, allowing ad libitum food intake on alternating days. A number of trials have shown benefit, but a randomized controlled trial directly comparing ADF to continuous daily calorie restriction had yet to be reported.
Other Articles in Issue #24 (October 2016)
Can vitamin D-crease pain?
Pain involves the nervous and immune systems, among others, so it can be tough to address through supplementation. Vitamin D's multitude of roles hint at its possible use as a pain treatment.
Interview: Josh Mitteldorf, PhD
Josh is well-known in the life-extension community, for looking deep into the literature and connecting the dots. We'll get his take on some interesting longevity-related topics. After 30 years wandering in the plasma physics of extragalactic radio sources, Mitteldorf came to the study of aging in 1996 to correct a fundamental error in the foundations of evolutionary theory. After 20 years, the revolution in biological concept of aging that he initiated is only now coming to fruition
When nitrate supplementation doesn’t involve supplements
We've covered several nitrate supplementation studies in previous ERDs. This trial is unique in that it studied the impact of a nitrate-rich diet on exercise performance.
The high cost of high heat cooking
The delicious browning and crusting of steak or chicken could also be harmful. This one-year long randomized trial looked at high-heat cooking versus gentler cooking, and its impact on insulin resistance.
Interview: Courtney Silverthorn, PhD
Are you in the life sciences, but not sure if you want to work in a lab? Courtney is uniquely qualified to give advice about this.
Does being insulin resistant affect weight loss on a low-fat or low-carb diet?
Weight loss is not a simple issue. The impact of a diet could be influenced by whether or not you’re insulin resistant, as examined by this one-year trial of a low-fat versus low-carb diet.
Examining the potential for edible sunscreen
Phytochemicals in plants are well known to have positive effects on chronic conditions, such as heart disease and cancer. But certain ones could also help you avoid ... sunburn.