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Intermittent Fasting vs Calorie Restriction for Weight loss and Diabetes

Intermittent Fasting vs Calorie Restriction

Intermittent fasting vs calorie restriction for weight loss and diabetes control are two commonly used nutritional interventions.

Both have been found effective, however, direct comparison of intermittent fasting vs calorie restriction for weight loss and blood glucose control have not been studied in head-to-head trials.

The study presented here has been published in JAMA. Participants in the study were enrolled in two nutritional interventions for 6 months: TRE or Time-restricted eating (intermittent fasting) and Calorie Restriction (CR).

Key points: Intermittent Fasting vs Calorie Restriction for Weight Loss and Diabetes

  • A recent clinical trial at the University of Illinois Chicago studied intermittent fasting for weight and glycemic control in type 2 diabetes (T2D).
  • The study spanned six months and involved T2D patients aged 18-80, randomly assigned to:
    • 8-hour time-restricted eating (TRE),
    • daily calorie restriction (CR), or
    • a control group.
  • Intermittent fasting led to a significant 3.56% reduction in body weight.
  • In contrast, the CR group showed a 1.78% reduction, while the control group remained relatively unchanged.
  • Intermittent fasting, without calorie counting, appears effective for weight loss and lowering HbA1c in T2D patients, with the need for more extensive trials to confirm these results.

intermittent fasting vs calorie restriction for weight loss and diabetes



Intermittent Fasting vs. calorie Restriction for Weight Loss and Diabetes:

Intermittent fasting, also called time-restricted eating, is a popular dieting method among individuals looking to lose pounds.

However, the benefits of this eating pattern are not restricted to weight loss only as people have experienced improved insulin sensitivity, blood pressure control, and cardiac health.

This fasting method involves food intake during a specified time window and living on only zero-caloric food for the rest of the day.

People frequently use the 8:16 method, where they eat for 8 hours and fast for 16 hours.

On the other hand, calorie restriction is a method that requires calculating calorie deficit per day and planning and prepping meals to adjust the calories. 

Calorie restriction and intermittent fasting have both been proven to improve cardiovascular health and blood glucose and are associated with some weight loss.

Calorie restriction and Intermittent fasting when used with Semaglutide, Mounjaro, or other weight loss medicines can have tremendous health effects.

Here are the Pros and Cons of Intermittent fasting vs Calorie restriction for weight loss and diabetes:


Intermittent Fasting (IF)

Calorie Restriction (CR)

Primary GoalDecide eating hours (when to eat)Decide and calculate your calories (how much to eat daily)
Eating PatternAlternating between eating and fastingReducing overall food and calorie intake daily
Meal FrequencyTake meals regardless of calories during specific hours with periods of fasting (calorie-free beverages and drinks allowed during the fasting period)Meals are taken at regular intervals without periods of fasting
Weight Loss PotentialEffective for weight lossEffective for weight loss
Metabolic EffectsImproves insulin sensitivity, cellular repair, visceral fat, blood lipids, and blood pressure.Improves insulin sensitivity, blood pressure, and blood glucose, and extends lifespan
ComplianceEasy. Does not require calorie countingDifficult. Requires calculating calories of each meal
Hunger ControlHelp control hunger during fasting periodsThis may lead to persistent hunger due to reduced calorie intake
Cardiovascular health and cognitionEffective for heart and brain healthEffective for heart and brain health
Risk of Nutrient DeficiencyLower risk as feeding pattern remains the sameHigher risk because of restricted diet
AdaptabilityEasier to sustain in the long runDifficult to sustain in the long run

Both Intermittent fasting and calorie-restricted diet are effective ways to lose weight and control blood glucose. Sticking to a specific diet plan is a personal choice.


Comparison of Intermittent fasting vs Calorie restriction for weight loss and Diabetes:

Similarly, in a study published in JAMA Network Open, the researcher followed 75 subjects for 6 months to analyze whether a time-restricted eating pattern is more effective for weight loss and decreasing hemoglobin A1c (HbA1c) levels than daily calorie restriction.

The subjects were all diagnosed with type-2 diabetes mellitus and obesity; their age range was between 18-80 years old.

The study’s conclusion supported that subjects with type-2 diabetes can experience better blood sugar control and weight loss by eating during an 8-hour window only.

This new revelation is beneficial for diabetics who are looking to enhance their quality of life.


Study’s Methodology and Analysis:

The 75 subjects included in this study were randomly assigned to three distinct intervention groups. The first intervention group was allotted a specific time to eat.

In time-restricted eating (TRE), the subjects were allowed to eat without any restrictions on calories from 12:00 p.m. – 8:00 p.m.

During the next 16 hours, subjects were restricted to eating zero-calorie beverages or water.

The other intervention group practiced a daily calorie-restriction (CR) diet, where the subjects had to cut down on their Kcal intake by 25%.

Each one acquired an individualized meal plan with the help of a study dietitian. Subjects in the control group were required to maintain their weight and routine habits.

Among all subjects, a significant improvement in weight reduction, loss of fat mass, and decrease in BMI were found in the TRE group only as compared to the controls and CR group.


Improvements in sugar control with intermittent fasting vs calorie restriction:

calorie restriction and weight loss
intermittent fasting vs calorie restriction for weight loss and diabetes

Dr. Krista Varady, a senior author of the study and a professor specializing in kinesiology and nutrition at the University of Illinois Chicago, stated that individuals in the time-restricted eating group reported greater ease in adhering to the regimen compared to those in the calorie-reduction group [Ref].

Both the Time-Restricted Eating (TRE) group and the Calorie Reduction (CR) group experienced a significant reduction in HbA1c levels when compared to the control group.

The reduction in HbA1c levels for the TRE group was approximately 0.91%, and for the CR group, it was about 0.94%.

Similarly, both the TRE and CR groups showed a decrease in mean glucose levels compared to the control group.

The TRE group had a reduction of approximately 42.53 mg/dL, and the CR group had a reduction of approximately 48.55 mg/dL.

Again, there was no significant difference in mean glucose reduction between the TRE and CR groups.


How is intermittent fasting more helpful for diabetics?

Krista Varady reported that subjects had an easier time sticking to an intermittent fasting regimen than calorie restriction.

This can be due to psychological reasons, as diabetics are always asked to cut back on calories, so eating with only a time restriction is easier.

The study reported that individuals in the TRE group stuck to the diet 87% of the days; meanwhile, those in the CR group only complied with the regimen 68% of the days during the 6-month intervention.

A previous literature review has also concluded that intermittent fasting is an efficient way to treat T2DM [Ref].

Furthermore, this fasting has proven to induce weight reduction and improve insulin sensitivity [Ref], both of which are common concerns in diabetics.

Another study revealed that IF could lower the need for diabetes medication, as experienced by 90% of the research’s subjects, while 55% of them entered diabetes remission and stopped taking diabetes meds [Ref].

intermittent fasting vs calorie restriction for weight loss and diabetes

The bottom line …

Intermittent fasting has repeatedly proven to be an effective non-medical treatment for diabetics who are looking to lose weight [Ref]. However, this is not common knowledge among T2DM patients.

The new study concluded the positive effects and improvement in HbA1c levels and blood sugar control in subjects in the TRE group (intermittent fasting).

Researchers added more to the importance of IF in a diabetic’s life, which is why effective control of blood sugar and improved insulin sensitivity should be focused on.

Considering the psychological implications of intermittent fasting, diabetics are more likely to practice this dieting regimen, and they should be encouraged to do so.

Physicians should stay educated on this topic and advise their patients to make positive changes in their dietary habits.


What do you think?

Written by Dr. Ahmed

I am Dr. Ahmed (MBBS; FCPS Medicine), an Internist and a practicing physician. I am in the medical field for over fifteen years working in one of the busiest hospitals and writing medical posts for over 5 years.

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