Semaglutide and Intermittent Fasting: Safety and Efficacy

Combining semaglutide with intermittent fasting may benefit blood sugar regulation and facilitate weight loss above combining semaglutide with a standard calorie restricted diet. However, more research is needed to directly study the combined effects of semaglutide and intermittent fasting due to increased risks of hypoglycaemia and gastric side effects. This article summarises all you need to know about semaglutide and intermittent fasting.
Klara Hatinova

Klara Hatinova

Klara is postgraduate researcher in experimental psychology at the
University of Oxford.

A blue image with text saying "Semaglutide and Intermittent Fasting: Safety and Efficacy"

Semaglutide: The Weight Loss Breakthrough

Semaglutide is a relatively new peptide for weight loss, similar to dulaglutide. Semaglutide mimics the role of Glucagon-like Peptide 1 (GLP1) in the body, stimulating the release of insulin, reducing blood sugar, and increasing satiety. Novo Nordisk markets it as Ozempic and Wegovy.

Semaglutide, combined with a calorie-restricted diet and exercise, can support weight loss, particularly in patients with one or more obesity-related comorbid conditions. These comorbid conditions include cardiovascular disease, hypertension, osteoarthritis, or other joint problems. In a seminal study over 68 weeks, patients who received semaglutide once a week lost 14.9% of their weight compared to 2.4% in the placebo group [1, 2]. Therefore, semaglutide is an economically efficient peptide for weight loss as it can alleviate the healthcare burden of obesity-related conditions [1, 3].

Intermittent Fasting: A Calorie Reduction Diet or Lifestyle Choice?

What is Intermittent Fasting?

Intermittent fasting (IF) is a dietary approach that alternates eating periods with fasting. It's a popular alternative to traditional dieting methods, typically involving daily caloric restriction. IF can take various forms, including alternate-day fasting, time-restricted feeding, and the 5:2 diet, which involves fasting for two non-consecutive days per week while eating normally throughout the remaining days [4, 5, 6].

The Science of Intermittent Fasting

The scientific literature provides some support for the benefits of IF. Studies have shown that IF can effectively reduce body weight, body fat, total cholesterol, and triglycerides in normal-weight, overweight, and obese individuals [5]. It's also been suggested that IF can help optimize energy metabolism, prevent obesity, and improve immune and reproductive function [6].

However, it's important to note that the long-term effects of IF are still not fully understood, and there's some debate about whether IF is superior to continuous caloric restriction, as typically used with semaglutide medication, regarding health and weight loss benefits [4, 7]. Some studies suggest that IF regimens are not superior to continuous caloric restriction in the long term [8].

Moreover, the optimal model of IF is still unclear, and more research is needed to understand the underlying cellular pathways that are activated during IF compared to caloric restriction [4, 6]. There are also concerns about the safety and feasibility of IF, which have not been well-studied to date [4].

Although IF has shown promise in some studies of metabolic health and weight loss, more research is needed to fully understand its long-term effects, safety and potential benefits. IF is likely to be a personal preference that may help specific individuals achieve their health goals, but not others.

Low Calorie Diets In Semaglutide Treatment

One of the cornerstones of successful semaglutide treatment is increasing physical activity and reducing caloric intake. This raises the debate as to which low-calorie diet is most suitable for semaglutide [9].

For example, a diet high in simple carbohydrates is unlikely to satisfy hunger and will not work for patients using semaglutide to manage type 2 diabetes.

Despite the importance of diet in managing diabetes and weight loss, there is a paucity of studies investigating different diets concurrently with semaglutide use. Therefore, in the following section, the evidence for semaglutide in diabetes and weight loss will be synthesized with the evidence for IF in diabetes and weight loss, highlighting the benefits and risks.

Intermittent Fasting and Semaglutide

The combination of intermittent fasting and semaglutide could benefit blood sugar. Semaglutide has been shown to significantly reduce blood glucose levels in people with type 2 diabetes. For instance, a study found that semaglutide 1.0 mg once weekly plus basal insulin significantly reduced mean HbA1c (a measure of long-term blood sugar control) compared to insulin when taken over 26 weeks [10].

Similar effects on blood sugar have been reported in intermittent fasting in a recent umbrella review, a type of scientific article that analyzes analyses of previous data [11]. Furthermore, intermittent fasting had better weight loss results compared to a standard low calorie diet. This suggests that semaglutide and intermittent fasting have common effects and intermittent fasting could be a good low calorie diet to practice alongside taking semaglutide.

While there is currently no direct evidence on the effects of combining intermittent fasting with semaglutide, the individual effects suggest potential benefits for blood sugar control. Furthermore, intermittent fasting may support weight loss in some individuals, depending on their personal preferences and lifestyle. However, it's crucial to consult a healthcare provider before starting any new dietary regimen or medication, as individual health conditions and needs can vary.

Risks of Intermittent Fasting and Semaglutide Combination

Combining intermittent fasting with semaglutide, a glucagon-like peptide-1 receptor agonist used for the treatment of type 2 diabetes and obesity, may present several risks.

  • Semaglutide delays gastric emptying, which could potentially interfere with the fasting and eating windows of intermittent fasting [11].
  • Semaglutide lowers blood sugar, increasing the risk of hypoglycemia. This risk can be exacerbated during prolonged fasting, especially when engaging in physical exercise [12].
  • Gastrointestinal side effects of Semaglutide: Semaglutide has been associated with gastrointestinal side effects, including nausea, vomiting, diarrhoea, constipation, and abdominal cramps [13]. Experiencing these symptoms may disrupt one’s ability to fast intermittently or vary caloric intake.
  • Increased risk of pancreatic disease: Another risk associated with semaglutide is the potential for an increased risk of biliary disease, such as cholelithiasis (gallstones) [14, 15]. However, the effect of intermittent fasting on this side effect is yet to be studied.

There are also risks to intermittent fasting:

Given the risks above, it's crucial to consult with a healthcare provider before starting any new medication or dietary regimen. Likewise, carefully consider your personal circumstances and evaluate whether intermittent fasting will be sustainable for you.

Summary: Semaglutide and Intermittent Fasting

To summarise, semaglutide is a type 2 diabetes drug and a weight loss drug that stabilizes blood sugar and can reduce weight, particularly if combined with a low-calorie diet. Intermittent fasting has also demonstrated benefits on blood sugar and could, therefore, be combined with semaglutide in diabetes treatment or weight loss. When combining semaglutide and intermittent fasting, it is critical to watch out for hypoglycemia, which may be more common.

Klara Hatinova

Klara Hatinova

Klara is a postgraduate researcher in experimental psychology at the University of Oxford. She has worked across a spectrum of hot topics in neuroscience, including her current project measuring reinforcement learning strategies in Parkinson’s disease. Previously, she studied the efficacy of psilocybin as a therapy for critical mental health conditions and examined molecular circadian rhythms of migraine disorders. She completed her undergraduate degree in Neuroscience at the University of Glasgow and participated in a year abroad at the University of California, where she worked on a clinical trial for spinal cord injury.