• Protein pacing means consuming protein at regular  intervals, while intermittent fasting involves alternating between  fasting and eating periods. 
  • A recent study  suggests that combining these two approaches may lead to superior weight  loss and better gut health and metabolic responses compared to a simple  calorie-restricted diet.
  • While this novel diet approach showed significant benefits, this study was small, and research on this type of diet is limited. 
  • Experts  recommend prioritizing a healthy gut microbiome and seeking  personalized weight management advice from licensed doctors or  dietitians.

A recent study published in Nature CommunicationsTrusted Source investigated the effects of two low-calorie diets on the gut microbiome and metabolomic profilesTrusted Source of individuals with overweight or obesity. 

This study built upon data and samples from a small randomized controlled trial that was published in ObesityTrusted Source in 2023. 

The  initial trial compared the benefits of two diets over 8 weeks: a simple  caloric restriction following approach versus a unique regimen  combining intermittent fasting and protein pacing.

Protein pacing involves consuming protein at consistent intervals throughout the day, while intermittent fasting alternates periods of fasting and eating.

Both  the caloric restriction and intermittent fasting and protein pacing  diets led to significant changes, but the intermittent fasting and  protein pacing group showed greater reductions in total body fat, visceral fat, weight, and desire to eat.

Contributing  to the original study findings, the new analysis suggests that the  intermittent fasting and protein pacing diet could significantly reduce  gastrointestinal symptoms and promote gut microbes associated with a  leaner body type. 

Additionally, the intermittent fasting  and protein pacing diet may increase beneficial proteins (cytokines)  and amino acid byproducts in the blood associated with weight and fat  loss.

The study was funded by Isagenix International LLC, which  provided the meal replacements, beverages, and supplements used in the  trial.

Continuous calorie restriction vs. intermittent fasting and protein-pacing

In  this study, Arizona State University researchers and their colleagues  analyzed data from a clinical trial involving 41 overweight or obese  individuals. 

Participants were randomly assigned to follow one of  two diets for 8 weeks: continuous calorie restriction or intermittent  fasting and protein-pacing. 

The caloric restriction diet  primarily consisted of whole foods, while the intermittent fasting and  protein pacing diet combined intermittent fasting with protein pacing,  including whole foods and supplement shakes and bars.

Both  diets reduced participants’ total fat, carbohydrate, sodium, sugar, and  calorie intake by approximately 40% from their baseline levels,  resulting in an average 1,000-calorie deficit.

The  intermittent fasting and protein pacing diet involved 5–6 days of 4  daily meals for women, and five meals a day for men, spaced 4 hours  apart, each containing 25–50 grams of protein, and included a 36–60-hour  weekly modified fasting period with 350–550 calories per day. 

Compared  to the caloric restriction diet, the intermittent fasting and protein  pacing diet significantly reduced sugar while increasing dietary fiber and protein. 

Despite many differences, the diets were matched for calorie intake and calories burned through physical activity. 

Participants self-reported their dietary intake daily, along with daily monitoring by researchers and weekly dietitian meetings.

Stool and blood samples were collected before, mid-intervention, and after the intervention to assess gut microbiome, cytokinesTrusted Source,  and metabolomic profiles. At the same intervals, participants completed  a 15-question gastrointestinal symptom rating scale (GSRS). 

The  study authors compared these markers between the two groups to identify  any significant differences in response to the two diets.

Benefits for weight management, gut health on both diets

The  initial study trial reported that both groups saw significant  improvements, however, the intermittent fasting and protein pacing group  witnessed greater improvements in their:

  • weight
  • total fat mass
  • visceral fat mass
  • desire to eat
  • fat-free mass percentage.

The  current analysis revealed significant changes in gut response to both  diet interventions, which might help account for the intermittent  fasting and protein pacing diet’s observed weight management advantages. 

Participants in the intermittent fasting and protein pacing group experienced:

  • notable improvements in gastrointestinal symptoms
  • a more substantial shift in gut microbiota
  • a greater overall change from baseline compared to the caloric restriction group.

The researchers noted increases in specific gut bacteria in the intermittent fasting and protein pacing group, particularly Christensenellaceae, which is associated with reduced visceral fat, improved fat oxidation, and enhanced metabolic health. 

Additionally,  intermittent fasting and protein pacing led to increased circulating  amino acid metabolites favoring fat oxidation and cytokines linked to  lipolysis (fat breakdown), weight loss, inflammation, and immune  response. 

Medical News Today spoke with Eliza Whitaker, MS, RDN,  a registered dietitian and medical nutrition advisor at Dietitian  Insights, who was not involved in the study and described the  significance of the intermittent fasting and protein pacing diet  outcomes. 

“Increases in amino acid-derived metabolites in  participants’ gut microbiome following an intermittent fasting protein  pacing regimen can supportTrusted Source energy, protein synthesis, and the proliferation of hepatocytes [involved in nutrient metabolism],” she told us. 

While  the intermittent fasting and protein pacing showed more significant  benefits overall, the caloric restriction diet notably displayed an  increase in metabolites associated with a longevity-related metabolic  pathway. 

The study also revealed a correlation between  individuals’ gut microbiome composition and their level of weight loss  in response to the diet interventions. 

How intermittent fasting and protein pacing may improve gut, metabolic health

MNT also spoke with Alexandra Filingeri, DCN, RDN, a registered dietitian and doctor of clinical nutrition who was not  involved with the study, about potential reasons why an intermittent  fasting and protein pacing resulted in superior gut and metabolic health  outcomes. 

She said that “[b]acteria that reside in the human  gastrointestinal tract produce bioactive metabolites known to influence  health.” 

Filingeri explained:

“The  bacterial environment within the gut shifts based on its specific  inputs. Essentially altering caloric consumption, fiber source and amino  acid availability can influence the type of bacteria in our gut. In the  [intermittent fasting and protein pacing], protein availability,  spacing between meals and fasting windows were shown to have positive  influence on microbial species.”

Thomas M. Holland, MD, MS,  a physician-scientist at the RUSH Institute for Healthy Aging, Rush  University System for Health, who was not involved in the study,  provided additional insight. 

Holland noted that while it  is difficult to pinpoint precisely why the intermittent fasting and  protein pacing diet resulted in more significant beneficial outcomes  than the caloric restriction diet, “the combination of intermittent  fasting and meal replacement with protein shakes may be key factors.”

“The  intermittent dietary input periods and the high protein content of the  shakes likely promoted gut microbiome competition. Furthermore, the  fiber in the shakes contribute[d] to better blood sugar control, reduced  cholesterol absorption (leading to lower LDL levels and improved  cardiovascular health), and enhanced general gut health, among other  benefits.”

– Thomas M. Holland, MD, MS

“This is not to say that calorie restriction alone wasn’t beneficial; it just wasn’t as impactful,” he emphasized. 

Hope for improving obesity management and precision nutrition

The  study highlights differences in gut microbiome and circling metabolites  connected to dietary interventions that facilitate weight loss and  alterations in body composition. These findings could help shape future  precision nutrition recommendations through larger and longer-duration  clinical studies.

Specifically, combined intermittent fasting and  protein-pacing dietary interventions may offer innovative approaches to  achieving healthy weight management and improving overall health  outcomes. 

However, the long-term practicality and safety of this  study’s particular approach to an intermittent fasting and  protein-pacing diet is not well-explored. 

“When it comes  to weight loss and gut health, it’s essential to consider precision  medicine and individual differences. Depending on one’s starting body  habits and goals, different diets will offer various benefits,” Holland  said. 

“Ultimately,” he highlighted, “a more diverse gut  microbiome improves digestion and nutrient absorption, which are  beneficial for overall health, including brain and cardiovascular  health.”

Holland concluded that both diet quantity and quality should be addressed for weight loss, ideally with guidance from a physician or registered dietitian. 

Intermittent fasting is a rather contentious topic when it comes to  health and well-being. While there are studies that point to its  short-term benefits such as reduced cholesterol when people eat within a 10-12 hour window, or an improved gut microbiome in people with obesity, there is some conflicting evidenceTrusted Source on its benefits for weight loss.

Some studies have also shown that intermittent fasting can help lower certain heart disease risk factorsTrusted Source,  such as reduced cholesterol and blood pressure. However, a recent  poster presented at EPI Lifestyle Scientific Sessions 2024 in Chicago  suggested that eating within an 8-hour time window may increase the risk of cardiovascular death by as much as 91%.

Considering  that time-restricted eating is a relatively new area of research,  experts agree that there is a lack of long-term studies on the effects  eating practices such as intermittent fasting have on the body, in  particular the cardiovascular system. 

In light of of these recent controversial findings, Feature Editor  Maria Cohut and I sat down to discuss all things intermittent fasting in  the latest instalment of our In Conversation podcast.

Joining us was Ali Javaheri, MD, PhD, assistant professor of medicine from the Center For Cardiovascular  Research at Washington University, who helped us answer questions, such  as: “How does intermittent fasting affect the body?”, “Is it safe for  everyone?”, and “What should we keep in mind if we decide to practice  it?”

Semaglutide, or GLP-1 receptor agonist drugs, are typically prescribed to people with type 2 diabetes to help them with blood sugar management by prompting their bodies to produce more insulinTrusted Source.

These drugs can also help with weight loss by suppressing a person’s appetite. At the moment, however, only one  semaglutide drug is approved as a weight management aid in people with  overweight and obesity in the United StatesTrusted Source and the United Kingdom. That drug is Wegovy.

Still,  a significant number of people who use semaglutide report hitting a  weight loss plateau that they find difficult to overcome.

How does semaglutide help with weight management, why do some people  on Wegovy hit a weight loss plateau, and what are some issues to keep in  mind when it comes to using semaglutide for weight loss?

In this instalment of our In Conversation podcast, Dr. Simon Cork,  senior lecturer in the Faculty of Health, Medicine and Social Care at  Anglia Ruskin University in the United Kingdom helps us answer these and  more questions.