2025年11月16日 / ライフスタイル

Health: How Long Should You Exercise to Really Lose Weight? ── The Reality of "150 Minutes a Week" as Shown by the Latest Research

Health: How Long Should You Exercise to Really Lose Weight? ── The Reality of "150 Minutes a Week" as Shown by the Latest Research

1. Why is "How long should I exercise to lose weight" important?

While there is an abundance of diet information out there,

  • catchphrases like "Lose -◯kg in ○ minutes a day"

  • or "Get a flat belly in two weeks"

often lack scientific backing and can lead to discouragement due to the gap with reality.


On the other hand,globally, obesity and overweight have nearly tripled in the past 45 years, affecting almost half of adults, contributing significantly to lifestyle diseases and mental health issues.ledauphine.com+1


This is why it is important to

understand, based on data, "how much weight or waistline can change with realistic exercise amounts and duration."
.


The article from Le Progrès addresses this very question by clearly introducing the latest meta-analysis research published in JAMA Network Open.ledauphine.com+1



2. Research Overview: The Relationship Between "Amount of Aerobic Exercise" and "Weight, Waist, Body Fat"

Research Design

  • Subjects:6,880 overweight or obese adults

  • Number of Trials:116 randomized controlled trials

  • Duration:At least 8 weeks

  • Intervention:

    • Aerobic exercises (walking, jogging, cycling, stationary biking)

    • Intensity: "Moderate to High"

  • Objective:

    • To investigate the relationship (dose-response) between "amount (minutes)" and "change" in weekly exercise time (minutes)

Main Results (Summary)

The study estimates changes in weight, body fat, and waist for each weekly aerobic exercise time. Key points are as follows:ledauphine.com+2ResearchGate+2

  • About 30 minutes a week (approximately 5 minutes a day)

    • Weight:About 0.5kg loss

    • Waist:About 0.6cm reduction

    • Body fat:Slightly less than 0.4% reduction
      → There is indeed improvement, but not enough to significantly change appearance.

  • 150 minutes a week (30 minutes per session × 5 days a week)

    • Weight:About 2.8kg loss

    • Waist:About 3.4cm reduction

    • Body fat:About 2.1% reduction
      → Considered a "meaningful change" by doctors, with noticeable differences around the waist.

  • 300 minutes a week (60 minutes per session × 5 days a week)

    • Weight:About 4.2kg loss

    • Waist:About 4.1cm reduction

    • Body fat:About 1.8% reduction (further decrease from 150 minutes)

The study also shows thatas exercise time increases, weight, waist, and body fat decrease almost linearly up to 300 minutes.



3. Conclusion: The guideline is "150 minutes or more of moderate to high-intensity aerobic exercise per week"

These research results align well with WHO and Japanese guidelines.

Consistency with WHO and National Guidelines

WHO and public agencies in various countries already recommend the following exercise amounts for adults:World Health Organization+2PMC+2

  • Moderate aerobic exercise: 150–300 minutes per week

  • or
    High-intensity aerobic exercise: 75–150 minutes per week

  • If possible, aiming for the upper limit of this range (300 minutes/150 minutes) for additional health benefits


The JAMA meta-analysis also concluded that

"150 minutes or more of moderate to high-intensity aerobic exercise per week is associated with clinically meaningful weight loss, body fat reduction, and waist reduction"
, providing scientific backing for international recommendation lines.PubMed+1

So, what does "moderate to high-intensity" mean?

As a guideline, consider the following:


  • Moderate exercise

    • Brisk walking (about 4–6 km/h)

    • Light jogging

    • Leisurely cycling
      → Intensity where "breathing is slightly labored, but conversation is possible"

  • High-intensity exercise

    • Running

    • Cycling at a speed that makes breathing hard

    • Interval training (such as HIIT)
      → Intensity where "short phrases can be spoken, but speaking in sentences is difficult"



4. How long should you continue to see results?

The trials included in this meta-analysis required programs ofat least 8 weeks. This means the research itself assumes

"Exercising continuously for more than 2 months"
.ledauphine.com+1


Combining insights from other literature and fitness practice, it generally looks like this:medecindirect.fr+1

  1. Weeks 1–2: Changes in condition precede weight changes

    • Slight improvement in sleep quality

    • Less fatigue

    • More positive mood

  2. Weeks 3–4: "Somewhat" noticeable changes in numbers

    • Weight fluctuates by about 0.5–1kg, with a gradual decrease in average

    • Climbing stairs becomes easier

  3. Weeks 6–8: Changes become noticeable to others

    • Weight: 2–3kg loss

    • Waist: Reduction of a few centimeters

    • Comments like "Your face and waist look a bit slimmer" start to appear

  4. 3 months to half a year