Fasting Is Required To See The Full Benefit Of Calorie Restriction In Mice
- Date:
- University of Wisconsin-Madison
- Summary:
- Over the last few decades, scientists have discovered that long-term calorie restriction provides a wealth of benefits in animals. Researchers have largely assumed that reduced food intake drove these benefits by reprogramming metabolism. But a new study finds that reduced calorie intake alone is not enough fasting is essential for mice to derive full benefit.
Over the last few decades, scientists have discovered that long-term calorie restriction provides a wealth of benefits in animals: lower weight, better blood sugar control, even longer lifespans.
Researchers have largely assumed that reduced food intake drove these benefits by reprogramming metabolism. But a new study from University of Wisconsin-Madison researchers finds that reduced calorie intake alone is not enough fasting is essential for mice to derive full benefit.
The new findings lend support to preliminary evidence that fasting can boost health in people, as trends like intermittent fasting continue to hold sway. These human and animal studies have added to the growing picture of how health is controlled by when and what we eat, not just how much.
The research further emphasizes the complexity of nutrition and metabolism and provides guidance to researchers trying to untangle the true causes of diet-induced health benefits in animals and humans.
This work was supported in part by the National Institutes of Health and the Department of Veterans Affairs .
Eating Too Much Sugar And High Glycemic Index Carbs With A Sedentary Lifestyle
Too much sugar is almost always a recipe for fat gain. Theres practically no way you can be burning all that sugar you are consuming. And sugar is digested fairly fast. So if youre not using it right away, it has to go somewhere. In most cases, itll get converted to body fat.
Now, because youre doing intermittent fasting for enough hours, youll be burning more calories than you would with a regular eating pattern, due to physiological changes happening in your body we have discussed earlier.
That being said, too much sugar is not healthy for you, neither is it good for intermittent fasting. In fact, most people who regularly consume big amounts of sugar, develop insulin sensitivity, which makes it a lot harder to fast because your body is always asking for food in general, and sugars in specific.
Thats why I suggest replacing some of these sugars with protein and healthy fats, resulting in a healthier lifestyle and an easier time committing to intermittent fasting.
What’s Next In Research
Most calorie-restriction and fasting-diet studies have been in younger people, but researchers are beginning to study older adults. A clinical trial conducted by NIA is testing the 5:2 diet in obese people, age 55 to 70, with insulin resistance. People in the experimental group can eat at will for 5 days, and then for 2 consecutive days are restricted to 500 to 600 calories per day. The experiment is designed to find out how 8 weeks of the 5:2 diet, compared to a regular diet, affects insulin resistance and the brain chemicals that play a role in Alzheimer’s disease.
In the coming years, researchers will continue to explore many unresolved questions. What are the long-term benefits and risks of the various eating patterns? Which diets are feasible as a long-term practice? What specific biological effects on aging and disease are triggered by a particular eating pattern? If a specific way of eating is recommended, at what age is it best to start, and is it safe to continue as you get older?
Scientists are exploring many aspects of calorie restriction and fasting and their effects on people of all ages. Some are conducting clinical studies and trials to learn more. If you are interested in volunteering for this type of research, search ClinicalTrials.gov using keywords such as “intermittent fasting,” “time-restricted feeding,” or “calorie restriction.”
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People Who Can Not Practice Intermittent Fasting
It should be noted just like any other diet intermittent fasting isnt for everyone. It is not advised to follow intermittent fasting if :
- You are pregnant. This is because pregnant women need a lot of calories to support pregnancy.
- You have a history of disordered eating.
- You dont sleep well or suffer from cases of insomnia.
- You are new to dieting and exercise.
- You are dealing with brittle diabetes.
Inclusion Criteria And Exclusion Criteria
Literature meeting all the following criteria would be included: The intervention group included but was not limited to ADF, TRF, IER, and Ramadan fasting, while the control group was the non-intervention diet or CR. The study provided physical and biochemical parameters of the subjects in both the intervention group and the control group after intervention. The follow-up time was at least 1 month. Data were available.
The study would be excluded once it met any of the following criteria: The study was not a randomized controlled trial . The research individual was not human. The full text of the article was not in English. The literature was duplicated.
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How Are We Doing Anyway
Thanks to advancements like improved sanitation, vaccination, the use of antibiotic and antiviral drugs, and life-lengthening treatments for cancer and heart disease, over the past few decades average life expectancy has steadily gone up.
Babies born in 2013 can expect to live to an average age of 78.7. Thats five years longer than the at-birth life expectancy in 1980. One study suggests that, assuming progress in medicine continues, life expectancy at birth could be about 90 by 2050.
Given this upward trend, why should we even care about aging?
Well, while our life expectancy may be increasing thanks to modern medicine, our health span the number of years were healthy and disease-free is shrinking.
According to the World Health Organization, more than a third of the U.S. population is obese. About the same proportion will be diabetic by 2050, if current lifestyle trends continue.
Sure, as a population, we live longer.
And thankfully, we think thats important now. Nobody floats us out to sea on an iceberg or leaves us behind to fend for ourselves the moment we become enfeebled.
But we dont always live better.
We survive, held together by the duct tape of pharmaceuticals and surgery. We get around as best we can with assistive devices and lifestyle kludges.
We survive but dont necessarily thrive.
Luckily, there are other options.
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Helps Manage Blood Sugar
Since obese people generally have high insulin resistance, they are at a higher risk of developing type 2 diabetes. Intermittent fasting can improve insulin resistance, which helps reduce blood sugar levels.
Fasting for extended periods can cause your insulin levels to drop, and the periodic insulin spikes are regulated. During a fast, you dont eat anything that spikes insulin, helping manage your blood sugar levels and lowering the risk of type 2 diabetes.
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Pros And Cons Ofintermittent Fasting
Here are the PROS of intermittent fasting:
- Periodic abstention from all calories activates autophagy and sirtuins a lot more than calorie restriction. Its a higher stressor that works intermittently.
- You can avoid metabolic adaptation as long as you refeed properly. Fasting should be done intermittently you fast and you feed. The extended gaps of not eating turn on your longevity genes much more strongly than just eating fewer calories.
- You can get away with eating more calories. It would be still important to practice some aspects of calorie restriction or at least eating around your maintenance but thanks to activating more autophagy in the fasted state you can potentially get away with even eating slightly more calories. Thats why people who are trying to build muscle can still get the longevity benefits of time-restricted eating.
- You can build muscle with intermittent fasting. As long as you get enough protein, calories, and train hard you can build muscle with some form of intermittent fasting whether that be 16/8 or OMAD.
- Fasting pretty much guarantees ketosis and autophagy. If you fast for 2-3 days, its almost impossible to not go into ketosis. Only in cases of severe insulin resistance or obesity would it take longer. Fasting also has other unique benefits like the activation of stem cells and immune system regeneration.
Here are the CONS of intermittent fasting:
What Are The Different Forms Of Calorie Restriction And Fasting
Calorie restriction is a consistent pattern of reducing average daily caloric intake, while fasting regimens primarily focus on the frequency of eating. The fasting diet may or may not involve a restriction in the intake of calories during non-fasting times.
There are a variety of fasting diets, sometimes called “intermittent fasting.” You may have read about:
- Time-restricted feedingMeals are consumed within a limited number of hours each day, with nothing consumed during the other hours.
- Alternate-day fastingEating is unrestricted every other day, and no or minimal calories can be consumed on the days in between.
- 5:2 eating patternEating is unrestricted for 5 straight days each week, followed by 2 days of restricted caloric intake.
- Periodic fastingCaloric intake is restricted for multiple consecutive days, such as 5 days in a row once a month, and unrestricted on all other days.
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Coronary Heart Disease Risk Indicator Assessment
Blood pressure and heart rate were measured in triplicate each week using a digital automatic blood pressure/heart rate monitor with the subject in a seated position after a 10-min rest. Fasting plasma glucose was measured in duplicate at week 1, 3, and 10 with a glucose hexokinase reagent kit . Insulin, C-reactive protein , homocysteine, adiponectin, and leptin were assessed in duplicate at week 1, 3, and 10 by ELISA .
Intermittent Fasting No Better For Weight Loss Than Just Counting Calories
In one of the longest trials of its type ever conducted researchers have found limiting food intake to a short period of time every day is no more effective a dietary strategy than simple calorie counting. The year-long experiment ultimately found calorie restriction to be the most important part of any weight loss plan.
Over the last decade fasting diets have increased in popularity, with advocates claiming they are the most effective way to lose weight and improve metabolic health. This dietary strategy can take a variety of forms, from alternate-day fasting to time-restricted feeding .
This new research focused specifically on a type of time-restricted feeding informally known as the 16:8 diet, which involves limiting all food intake to an eight-hour period every day. In this case the trial limited its fasting cohort to eating only between 8 am and 4 pm.
The trial recruited 139 subjects, all either overweight or obese but otherwise healthy. The cohort was randomly split into two groups: one group tasked with a time-restricted feeding strategy and another that could eat at any time. Both groups were required to limit their caloric intake each day: men no more than 1,800 calories and women no more than 1,500 calories. The trial lasted 12 months.
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What To Do Next
As it stands, we dont have enough evidence to safely recommend long-term CR as an anti-aging strategy.
Remember: CR can put you at risk for malnutrition. And because it appears to require protein restriction, CRs health risks probably outweigh the potential benefits.
Not to mention that CR is a major commitment that would be tough to balance with any kind of social life.
All in all, IF seems like a better bet than CR for those hunting for the Fountain of Youth .
Benefits Of Intermittent Fasting
Intermittent fasting has become popular in the healthcare industry, particularly among people dealing with weight gain . IF combined with exercise can benefit people struggling with obesity and eating disorders. Studies have shown that intermittent fasting can cure or prevent heart disease, stroke, aging, type 2 diabetes, etc.
Here is a closer look at some benefits of the 5:2 IF diet.
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What Are The Benefits Of Intermittent Fasting
Despite the concerns, there are benefits to this dietary approach.
- Findings from studies indicate it may possibly lower the risk of cancer.
- From a behavioral perspective, it may be possible to use the concept of intermittent fasting without the severe restriction of calories. A protocol that might limit food by using a nutritional supplement will result in a smaller restriction of calories without sacrificing nutrition on fasting days. This may prove to be a safe and helpful method for long term weight management success.
- There is significant interest in the use of intermittent fasting to help stem the obesity epidemic in the United States. Further studies will help to define its possible role.
The use of intermittent fasting as a viable, and potentially beneficial, dietary protocol requires further study. If you are considering this approach, please be sure to speak with your physician.
If you are trying to lose weight, we have many programs that can help. Visit our website to learn more.
What Is The Best Intermittent Fasting Plan For Weight Loss
Dr Sam Watts, founder of Mind Body Medical , tells Live Science that there are two clear leaders when it comes to intermittent fasting styles. Lots of clinical evidence exists around the potential weight loss benefits of different intermittent fasting plans, he says. For quicker and more profound weight loss, the alternate day fasting plan is arguably the most effective. A less-extreme and thus easier-to-adopt approach is the 16:8 model. This is a time-restricted eating version of intermittent fasting that involves consuming all of your calories in an eight-hour window and fasting for the remaining 16 hours.
This approach has consistently been shown to induce significant and progressive weight loss in an arguably more sustainable model.
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Health Benefits Of Intermittent Fasting
There are very few studies on the 5:2 diet specifically.
However, there are plenty of studies on intermittent fasting in general, which show impressive health benefits (
After 12 weeks, the fasting group had:
- Reduced body weight by more than 11 pounds .
- Reduced fat mass by 7.7 pounds , with no change in muscle mass.
- Reduced blood levels of triglycerides by 20%.
- Increased LDL particle size, which is a good thing.
- Reduced levels of C-reactive protein , an important marker of inflammation.
- Decreased levels of leptin by up to 40%.
Summary
The 5:2 diet may have several impressive health benefits, including weight loss, reduced insulin resistance, and decreased inflammation. It may also improve blood lipids.
What Does Calorie Restriction Do
Calorie restriction is the act of reducing your intake of daily calories below what your average might be, while still getting the nutrition your body needs. Many studies have suggested that calorie restriction imparts health benefits: For example, in a long-term study called CALERIE, scientists found that in normal and slightly overweight adults, a 25 percent calorie restriction led to reduced fat mass and better overall markers for heart and metabolic health. These include LDL cholesterol, blood pressure, insulin sensitivity, and others.
Many people are told by physicians to restrict calories for weight loss and these potentially connected health benefits. Of course, calorie restriction for weight loss linked to appearance and, some might argue, a narrowly defined standard of aesthetics is also common. Almost every calorie-restricting fad diet from Weight Watchers to juice cleanses promises to transform waistlines, not blood glucose levels.
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Neuroendocrine Adaptations To Fasting
Fasting, especially if prolonged, is associated with several neuroendocrine adaptations, including increased secretion of cortisol, glucagon, adiponectin, growth hormone, and melatonin and decreased secretion of insulin, leptin, and thyroid hormones . Of the latter adaptations, the downregulation of leptin secretion exerts the most pertinent effect on energy balance. Leptin is a polypeptide hormone derived from adipocytes that bind to specific receptors in the hypothalamus to signal satiety and decrease energy intake. Leptin levels decrease dramatically during fasting, and such a drop is associated with decreased energy expenditure and increased appetite, which could hinder the desired weight loss . Leptin supplementation has been shown to prevent the impulse of weight regain in the post-obese state . Thus, there is a need to study the effect of IF on leptin expression to determine whether persistent leptin suppression might be a factor weighing against the sustained efficacy of IF as a weight loss strategy.
Fasting And Weight Loss
The scientists recruited 36 lean, healthy adults in the U.K. between 2015 and 2018 for the study and monitored their baseline diet and physical activity for 4 weeks. They then randomly allocated the participants to one of three groups of 12.
The participants in the first group, the energy restriction group, consumed 75% of their normal energy intake each day.
The second group used two methods of weight loss: fasting and energy restriction. They fasted on alternate days and consumed 150% of their regular calorie intake on their eating days.
The third group did not face any energy restriction. They fasted on alternate days and consumed 200% of their regular calorie intake on their eating days.
The fasting groups consumed no energy-providing nutrients during their fasting periods. This ensured that their dietary interventions were standardized and allowed enough time for fasting-related bodily functions to activate.
The participants underwent various lab tests before and after the 3-week intervention. The researchers also monitored the participants diet and physical activity levels throughout and extracted fat tissue samples from some individuals.
Those on energy restriction diets lost an average of 1.91 kilograms at the end of the study period. Meanwhile, those fasting with energy restriction lost an average of 1.60 kg, and those fasting without energy restriction lost an average of 0.52 kg.
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