FM Coaching · Fitness Research

Intermittent Fasting and Exercise: New 2026 Trial Shows Short-Term Fat Loss, but What Lasts?

A randomised trial of 187 adults found extra 12-week weight loss with time-restricted eating, but no significant additional liver-fat reduction and no lasting between-group difference in weight at one year.

By FM Coaching Editorial Team · Published 28 October 2026 at 07:19 UK

intermittent fasting and exercise — Intermittent Fasting & Exercise: 2026 Trial, 1-Year Results FM Coaching · fm coaching

Intermittent fasting delivered more short-term weight loss in a new randomised study—but the headline changes when you look a year later. A University of Granada trial involving 187 adults with obesity tested an eight-hour daily eating window, supervised exercise, both strategies together, and usual care. After 12 weeks, the fasting groups lost about 2.2 kg more weight than usual care on average; the combined programme also reduced total body fat more than either usual care or exercise alone. Yet the primary liver-fat result was not significantly better, and the early differences in weight and body composition were no longer detectable between groups at one-year follow-up.

FM Coaching Fitness Research | Evidence desk | Study published 14 October 2026; university research update 22 October 2026; checked 28 October 2026.

The result offers a more useful question than “does fasting work?”: what changes during an intervention, which outcomes actually improved, and how can people maintain progress after structured support stops? Here is what the trial says—and what it does not.

The evidence in 30 seconds: three things to know

Weight: The two groups assigned an eight-hour eating window lost about 2.2 kg more than usual care on average over 12 weeks.
Liver fat: None of the three active interventions achieved a statistically significant additional reduction over usual care on the trial’s primary MRI-measured outcome.
Durability: At one-year follow-up, the original between-group weight and body-composition differences were no longer detectable.

This was a randomised controlled trial published in Nature Communications, not a social-media challenge. The University of Granada’s research release offers a useful explanation of the outcomes. Both should be read before drawing conclusions about fasting for an individual person.

Four approaches, one test: what the researchers actually compared

All four groups received education about Mediterranean-style eating and physical activity. The additional assignments were different. That matters: the control group was usual care, not “doing nothing”, and the exercise programme was supervised rather than a vague recommendation to move more.

Trial group	Participants	What was added over the 12 weeks?	What the group can tell us
Usual care	48	Mediterranean diet and activity education	Reference for the other three groups
Time-restricted eating	46	Daily meals within an eight-hour window	What meal timing may add beyond usual care
Supervised exercise	47	Structured resistance and high-intensity aerobic training	What supervised training may add
Time-restricted eating + exercise	46	Eight-hour eating window plus supervised training	Whether combining both changes outcomes

Participants were recruited in Granada, Spain, and half were women. The researchers assessed liver-fat fraction by magnetic resonance imaging (MRI); the primary comparison was at 12 weeks. Fitness, body weight and body composition were among the additional outcomes.

What improved after 12 weeks—and what did not?

The weight-loss result: a useful difference, not an automatic prediction

People in the fasting-only and fasting-plus-exercise groups lost approximately 2.2 kg more than the usual-care group on average. This is an average between-group difference; it does not mean everybody lost 2.2 kg, that 2.2 kg was the full amount lost, or that the result applies to people with every starting weight and health status.

The combined group had greater body-fat loss than usual care and supervised exercise alone. The university also reported improved cardiorespiratory fitness among exercise participants. These are different kinds of progress: scale weight, fat mass and aerobic fitness should not be treated as interchangeable measurements.

Why the primary liver-fat finding is the headline correction

The study was designed primarily to test whether the programmes caused a greater reduction in intrahepatic fat fraction—fat measured within the liver—than usual care. All groups showed reductions, but the additional changes compared with usual care were not statistically significant:

Intervention vs usual care	Estimated difference in liver-fat fraction	95% confidence interval	Statistically significant?
Time-restricted eating	−0.4 percentage points	−2.0 to +1.2	No
Supervised exercise	−0.8 percentage points	−2.4 to +0.8	No
Combined programme	−1.1 percentage points	−2.7 to +0.5	No

All three confidence intervals include zero. The figures above are comparisons with usual care, not the total amount of liver fat lost by each group. This is precisely why it would be inaccurate to say the new trial proved fasting “reverses fatty liver”.

The researchers also described an exploratory analysis among participants who began the trial with fatty liver: roughly 30% of the combined group versus 6.5% of usual care no longer met that condition’s study-defined threshold. That subgroup finding is interesting but does not overturn the non-significant primary result or establish a treatment recommendation.

The one-year result that changes the conversation

The Granada team followed up after the initial programme. At that later point, there were no detectable between-group differences in weight, body composition or liver-fat change of the kind seen at 12 weeks. This does not prove every participant regained all the weight, and it does not mean exercise has no long-term value. It means the trial did not establish that its short-term advantage over the comparison groups persisted.

Question	At 12 weeks	At one-year follow-up
Weight and body composition	Fasting groups showed extra weight loss; combined group showed extra body-fat loss in reported comparisons	Earlier between-group differences no longer detectable
Liver fat (primary outcome)	No statistically significant additional reduction over usual care	No between-group difference detected
Fitness	Exercise groups showed cardiorespiratory fitness improvements	Do not assume the same fitness differences persisted without checking the full study
Practical conclusion	A short programme can change habits and measurements	Long-term support and repeatable routines deserve more research

This is an important distinction for anyone following fitness research. Short-term intervention success and lasting maintenance are two separate questions; an article that reports only the first half of the experiment misses the more interesting part of the story.

Does this mean intermittent fasting beats ordinary dieting?

No—not on the evidence of this trial. TEMPUS compared several strategies against education-based usual care. It did not directly compare every meal-timing strategy with an equally intensive, calorie-matched conventional diet for years. A separate 2026 Cochrane review of 22 randomised trials, involving 1,995 adults, found intermittent fasting generally did not lead to a clinically meaningful advantage over regular dietary advice for weight loss.

Both results can be true. A structured eating window may help some individuals eat less and adhere to a plan during a 12-week programme, without meal timing being inherently superior to a sustainable energy deficit. NICE guidance also emphasises an individualised, nutritionally balanced approach that can be maintained. Read NICE’s obesity-management recommendations.

What about the 16:8 diet?

The trial used an eight-hour eating window, commonly called 16:8 because it leaves roughly 16 hours outside that window. It did not establish that 16:8 is the ideal schedule for everybody, that 5:2 fasting would produce the same results, or that a longer fast would be better. Eating-window timing is only one part of what people actually eat and how they live.

A practical reader's guide: fasting and exercise without losing sight of recovery

For healthy adults interested in exercise, the useful takeaway is not “start fasting tomorrow”. It is to consider whether a repeatable eating pattern supports sufficient nutrition, training quality, sleep and a realistic weekly routine. Someone with medical concerns or medication risks should discuss fasting with a qualified healthcare professional first.

A realistic week built around two strength sessions

The following is an illustrative general-fitness schedule, not the TEMPUS training prescription and not a personalised medical plan. It can be followed without intermittent fasting at all. Start at an appropriate level and build gradually.

Day	Movement focus	Purpose
Monday	Full-body strength: squat or sit-to-stand, row, press, hinge and carry	Practise major movement patterns
Tuesday	Moderate walk or cycle, 20–35 minutes	Build aerobic consistency
Wednesday	Recovery or gentle walk	Adapt to fatigue and schedule
Thursday	Full-body strength: split squat variation, pull, push, hip hinge and core	Repeat strength work with progression
Friday	Moderate activity, 20–35 minutes	Cardiorespiratory fitness
Weekend	Enjoyable walking, cycling or mobility as tolerated	Consistency rather than punishment

For many adults, the NHS guideline is to build towards 150 minutes of moderate aerobic activity each week and strengthening activity on at least two days. That is a health target, not a promise of specific weight loss.

How to decide when to eat around training

Situation	Practical consideration
You train before work	A breakfast-inclusive eating pattern may be easier than forcing workouts on an empty stomach
You lift in the evening	Allow enough opportunity for a useful meal before and after training; do not force a narrow window that undermines recovery
Training feels weak or you feel faint	Stop and reassess; do not treat dizziness or poor performance as proof a fast is “working”
You cannot meet normal nutrition needs	A less restrictive schedule or no time restriction may be more suitable

Fasting is not a prerequisite for building strength. For a person pursuing fat loss and resistance training, the quality of the programme, balanced nutrition and long-term consistency matter. FM Coaching's fat-loss coaching and muscle-building support focus on individualised training and nutrition guidance, not medical fasting prescriptions.

What a scale reading cannot tell you

The TEMPUS report monitored body weight, fat mass, liver fat and fitness because each answers a different question. For everyday training, people may also find it useful to monitor exercise consistency, strength progression, walking tolerance, how their routines fit family or work, and whether they can maintain their eating pattern. Scale fluctuations alone cannot show whether somebody is stronger, fitter or building sustainable habits.

When comparing health claims online, look for the actual outcome measured, the control group, the duration and what happened after the intervention ended. A dramatic headline about “more fat loss” can leave out the primary outcome, and a single short-term result should not be treated as a guarantee of lifelong weight control.

Six claims the study does not justify

“Fasting cured fatty liver.” The primary between-group liver-fat outcome was not significant.
“Everyone lost 2.2 kg.” The reported figure was an average extra difference versus usual care.
“Fasting plus HIIT is superior for everyone.” The study enrolled a defined population of adults with obesity in a supervised setting.
“Results lasted for a year.” Between-group differences were no longer detectable at follow-up.
“Women respond worse than men.” Exploratory sex-specific signals were not sufficient to establish a real sex difference.
“A longer fast must work better.” The trial did not compare escalating fasting windows or multi-day fasting.

Who should be especially cautious?

Intermittent fasting is not a universal recommendation. NHS-linked guidance advises against it in pregnancy, breastfeeding and for people with a history of eating disorders. People with diabetes, particularly those using insulin or medicines that can cause low blood glucose, need individual advice before changing meal timing. Other medical conditions, a history of under-fuelling, or difficulty meeting nutritional needs are also reasons to seek professional assessment. See UK diabetes fasting guidance.

This article is general research reporting and exercise education. It is not treatment advice for obesity, diabetes or metabolic dysfunction-associated steatotic liver disease (MASLD). Do not change prescribed medication or pursue very-low-energy dieting on the basis of an online article.

FM Coaching analysis: the more useful question is what you can repeat

The most actionable lesson of TEMPUS may be about maintenance. Short-term structure can change behaviour; keeping the benefits is another challenge. An eating window is one possible tool, not the goal itself. A realistic fitness plan considers preferred foods, strength training, available time, recovery and the support someone needs to continue.

FM Coaching provides online fitness coaching and a library of practical fitness guides. Coaching supports training and everyday habits; it is independent of the Granada researchers and does not diagnose or treat medical conditions.

Research sources and editorial method

This report is based primarily on the TEMPUS randomised trial published in Nature Communications (Clavero-Jimeno and colleagues, 14 October 2026; DOI: 10.1038/s41467-026-78625-3), supplemented by the University of Granada’s 22 October summary, the 2026 Cochrane evidence review, NICE guidance and NHS activity recommendations. The training schedule is an FM Coaching illustrative example, not a protocol administered in the trial.

Correction standard: If new trial data or an erratum changes the interpretation, update this article at the same URL and mark the actual modification date. The authors of the study did not provide an interview for this report.

Intermittent fasting and exercise: frequently asked questions

Does intermittent fasting work better when combined with exercise?

In the 2026 TEMPUS trial, combining an eight-hour eating window with supervised exercise improved some short-term body-fat outcomes. But the primary liver-fat outcome was not significantly better than usual care, and longer-term between-group weight differences were not detected.

What did the 2026 intermittent fasting and exercise study find?

The trial enrolled 187 adults with obesity. Both fasting groups lost about 2.2 kg more than usual care on average at 12 weeks. The combination helped body-fat outcomes, but liver-fat reduction was not significantly greater than usual care.

Is an eight-hour eating window the same as 16:8 fasting?

Yes. Eight hours of eating and roughly 16 hours outside that window is commonly called 16:8. The study did not compare every fasting schedule.

Did fasting and exercise reduce liver fat?

Liver fat decreased across groups, but the additional reduction compared with usual care was not statistically significant on the trial’s main MRI-measured outcome.

Did the TEMPUS benefits last one year?

The between-group differences in weight and body composition observed at 12 weeks were no longer detectable at the one-year follow-up. That does not tell us that every individual regained the same amount of weight.

How much extra weight did the fasting groups lose?

About 2.2 kg more on average than usual care over 12 weeks. It is a between-group difference, not a guaranteed weight loss for any participant.

Is intermittent fasting better than a normal calorie deficit?

The TEMPUS trial does not establish that. A 2026 Cochrane review found little to no clinically meaningful weight-loss advantage compared with standard dietary advice, although individual preferences and adherence may differ.

Can I lift weights during intermittent fasting?

Many healthy adults can combine lifting with a suitable meal schedule, but they still need adequate food, recovery and hydration. Training quality and personal medical circumstances matter more than forcing a particular window.

Should I do fasted cardio for more fat loss?

TEMPUS did not test whether fasted workouts beat fed workouts under otherwise matched conditions. Choose an approach that supports consistent exercise and wellbeing rather than relying on an assumed fasted-cardio advantage.

Is HIIT necessary for weight loss with fasting?

No. The trial used supervised resistance exercise and high-intensity aerobic training, but it did not show that every individual must do HIIT. Walking, other aerobic activity and strength training can be adapted to ability.

Does fasting make you lose muscle?

The study does not establish a simple rule that fasting causes or prevents muscle loss. Changes in fat-free mass and strength are separate outcomes; sufficient nutrition and progressive resistance training are important considerations.

Did the study include women?

Yes, approximately half of the 187 participants were women. Exploratory differences between men and women were not enough to prove different treatment responses by sex.

Can intermittent fasting cure fatty liver disease?

No. This 2026 trial did not show a statistically significant benefit for its primary liver-fat endpoint compared with usual care. Liver disease requires individual clinical assessment and treatment.

Is intermittent fasting safe for people with diabetes?

Fasting can increase hypoglycaemia risks for people using certain diabetes medicines, including insulin and some tablets. Discuss any meal-timing change with the diabetes healthcare team first.

Who should avoid intermittent fasting?

People who are pregnant, breastfeeding or have a history of eating disorders should not attempt restrictive fasting without specialist medical advice. People with medical conditions or medications also need individual guidance.

Can I do 5:2 instead of 16:8 and expect the same result?

No. The TEMPUS participants used eight-hour daily time-restricted eating. The trial did not test a 5:2 programme or establish equivalent results.

What should I track besides scale weight?

Depending on your goals, useful measures include strength, aerobic fitness, movement consistency, wellbeing and sustainable food habits. Clinical conditions need clinician-directed measures.

Where can I read the original 2026 fasting study?

The paper is in Nature Communications, DOI 10.1038/s41467-026-78625-3. The University of Granada also published an accessible study summary on 22 October 2026.

Can I use the study to design my own medical weight-loss plan?

No. The findings are population-level evidence from a supervised trial and do not replace advice from a qualified clinician or registered dietitian.

Does FM Coaching prescribe fasting or treat obesity?

No. FM Coaching provides personalised exercise and general nutrition support; medical weight management and treatment decisions belong with appropriately qualified healthcare professionals.