There are more types of diets published in books and on the internet/social media than anyone can possibly account for. This fact of course, has led to a great deal of confusion regarding what we should eat or not eat and what type of diet is the most suitable for the achievement of a given individual’s health goals.
A case in point is the intermittent fasting diet or program for quick and sustainable weight-loss/management. In this article, I will actually reveal the facts from a scientifically-based rationale rather than using pseudoscience and heresay regarding the validity and efficacy of this diet.
Intermittent fasting utilizes cycles of fasting, (no food or a significant reduction in calories) with various periods of unrestricted eating. The diet proposes to alter body composition by reducing body fat while improving risk factors for disease like reductions in resting blood pressure and cholesterol. The basis of this diet are derived from traditional fasting , which can be traced to the time of Plato. Traditional fasting practices typically involves a steady abstinence of food and certain beverages which can range from one day to one month. Depending upon the type and reason for fasting, this may require complete abstinence or alternatively, allow a for reduced amount of food and beverages consumed at a certain time.
Intermittent fasting was developed after some research had previous indicated that prolonged very low calorie diets could cause physiological adaptive changes forcing the body to make certain physiological changes to the calorie restriction to the extent that further weight loss would be prevented. The purpose of intermittent fasting was intended to address this problem by cycling between a low calorie level for a brief time followed by normal eating, which may prevent these adaptations. However, continued research does not and has not consistently shown that intermittent fasting is superior to continuous low calorie diets for weight loss efficiency.
In fact, the research has gone even further, low calorie diets only work temporarily and have no place and long-term weight management!
- “Alternate-day fasting—Alternating between days of no food restriction with days that consist of one meal that provides about 25% of daily calorie needs. Example: Mon-Wed-Fri consists of fasting, while alternate days have no food restrictions.
- Whole-day fasting—1-2 days per week of complete fasting or up to 25% of daily calorie needs, with no food restriction on the other days. Example: The 5:2 diet approach advocates no food restriction five days of the week, cycled with a 400-500 calorie diet the other two days of the week.
- Time-restricted feeding—Following a meal plan each day with a designated time frame for fasting. Example: Meals are eaten from 8am-3pm, with fasting during the remaining hours of the day.”
This is the recipe for the intermittent fasting diet.
Some research points to consider:
A systematic review of 40 studies found that intermittent fasting was helpful for weight loss, (7-11 pounds over 10 weeks). However, there was a large degree of variability in the studies, ranging in sample size from 4 to 334 subjects, with different follow-up periods (2 to 104 weeks). Another important fact to consider was that different study designs and methods of intermittent fasting were utilized, and the participant physical and metabolic characteristics differed (lean vs. obese). In addition, 50% of the studies were controlled trials comparing the fasting group to a comparison group and/or a control group (either continuous calorie restriction or usual lifestyle), with the other half examining an intermittent fasting group alone.Here is a brief summary of their findings:
- “Dropout rates ranged from 0-65%. When comparing dropout rates between the fasting groups and continuous calorie restriction groups, no significant differences were found. Overall, the review did not find that intermittent fasting had a low dropout rate, and therefore was not necessarily easier to follow than other weight loss approaches.
- When examining the 12 clinical trials that compared the fasting group with the continuous calorie restriction group, there was no significant difference in weight loss amounts or body composition changes.
- Ten trials that investigated changes in appetite did not show an overall increase in appetite in the intermittent fasting groups despite significant weight loss and decreases in leptin hormone levels (a hormone that suppresses appetite).”
In a more reliable randomized controlled trial. This trial followed 100 obese individuals for one year and subsequently did not find intermittent fasting to be more effective than daily calorie restriction. Below are the key findings of this trial.
- “No significant differences in weight loss, weight regain, or body composition (e.g., fat mass, lean mass).
- No significant differences in blood pressure, heart rate, fasting glucose, and fasting insulin. At 12 months, although there were no differences in total cholesterol and triglycerides, the alternate-day fasting group showed significantly increased LDL cholesterol levels. The authors did not comment on a possible cause.
- The dropout rate was higher in the alternate-day fasting group (38%) than in the daily calorie restriction group (29%). Interestingly, those in the fasting group actually ate less food than prescribed on non-fasting days though they ate more food than prescribed on fasting days.”
Although there are benefits to brief periods of caloric restriction previously demonstrated in animal studies., similar benefits of intermittent fasting in humans have not been observed. At this point there is no evidence to conclude that intermittent fasting is superior to other weight loss/management methods with regard to the degree of weight loss, biological changes, compliance rates, and decreased appetite. Certain people who typically eat one or two meals a day or do not eat for long stretches of time may show better compliance with this type of regimen. This diet is not suitable for diabetics, nursing mothers, folks with eating disorders, adolescents and those people who need to take food with regular medications.
Sustainable weight management really needs to be directed at the cause and not some theory extrapolated from animal studies.
We eat too much of the wrong types of calories and don’t get enough exercise! Humans have evolved into fat storage machines not like our ancestors who were fat burners. We created our genes that are responsible for this to greatly be up-regulated because of our lifestyle.
You can’t fool mother nature!
Until Next Time
The Vitality Project
Dr. Kevin J. McLaughlin