Magnify the Effects
Move. Repeat. Fuel up. Each one powers the others.
🌅 Coach Sunny: "You don't have to feel like it. Shoes on, door open. That's the win."
Key findings
- In the SMILES trial, 32.3% of the diet group reached remission vs 8.0% of controls (NNT 4.1); a small trial. (Jacka FN et al. 2017)
- Across 16 RCTs, dietary interventions reduced depressive symptoms (g 0.16). (Firth J et al. 2019)
- Building a habit took 18 to 254 days, and missing one day didn't derail it. (Lally P 2010)
How moving helps
1. Movement is the spark
One session lifts your energy and focus a little, and regular movement helps with mood (see Lift Your Mood). That first win makes the next good choice easier.
2. Discipline is the daily loop
Habits grow by repeating the same action in the same context, like a walk right after breakfast. In a real-world habit study, reaching near-automatic took anywhere from 18 to 254 days, and missing one day didn't materially affect it (Lally 2010). So skip perfection and keep the streak alive most days.
3. Diet is the multiplier
In the SMILES trial, 67 adults with moderate to severe depression had 7 sessions with a dietitian over 12 weeks to move toward a modified Mediterranean diet. The comparison group got social support on the same schedule. The diet group improved about 7.1 points more on the MADRS depression scale (Cohen's d −1.16), and 32.3% reached remission vs 8.0% (Jacka 2017).
Read it honestly: it was a small trial that fell short of its planned sample size, and participants couldn't be blinded, so expectations may have played a part. It was funded by Australia's NHMRC; Woolworths provided food vouchers and Meat & Livestock Australia funded the blood tests, and the sponsors had no role in the design or analysis. A meta-analysis of 16 diet trials found a smaller but real benefit for depressive symptoms (Firth 2019).
What this means: About 1 in 3 people in the diet group reached remission, compared with about 1 in 12 in the comparison group. Roughly 4 people needed the program for one extra remission (NNT 4.1). It was a small trial, and participants knew which group they were in.
Source: Jacka et al. 2017, BMC Medicine, SMILES trial (open access, CC BY 4.0), 67 adults with moderate to severe depression. Redrawn from the published numbers. doi:10.1186/s12916-017-0791-y
What this means: Across mostly non-clinical groups, better diets gave a small reduction in depressive symptoms and no clear change in anxiety. By convention an effect size of about 0.2 is small, 0.5 medium and 0.8 large.
Source: Firth et al. 2019, Psychosomatic Medicine, 45,826 participants. doi:10.1097/PSY.0000000000000673
Your next 15 minutes
- Move daily: 10 minutes counts.
- Keep the streak: same time, same cue. Missed a day? Just go again tomorrow.
- Eat mostly whole foods: vegetables, fruit, whole grains, legumes, fish, olive oil and nuts, and fewer ultra-processed foods.
- These are general ideas, not a diet plan or medical advice. A doctor or dietitian can tailor them to you.
💪 Jumpstart: if you have time to read this, you have time for 10 push-ups (knees count). Seriously, actually do it. Now. Then come back three times a week and do it again.
Start the free 21-day habit builder →Quick answers
What is the SMILES trial?
A 12-week randomised trial in 67 adults with depression. A dietitian-led modified Mediterranean diet beat social support on depression scores and remission.
How long does a habit take?
In one study it ranged from 18 to 254 days. Missing a single day didn't materially affect it, so just keep going.
Is this a diet plan?
No. These are general ideas, not medical or dietary advice. Talk to your doctor or a dietitian.
The research (verified against the published abstracts)
- Jacka FN et al. (2017). A randomised controlled trial of dietary improvement for adults with major depression (the 'SMILES' trial). BMC Medicine 15:23. doi:10.1186/s12916-017-0791-y
67 adults with moderate to severe depression; 12 weeks; 7 dietitian sessions (modified Mediterranean diet) vs a social-support control. The diet group improved significantly more on the MADRS (Cohen's d −1.16; about 7.1 points more). Remission: 32.3% (10 of 31) vs 8.0% (2 of 25); NNT 4.1 (95% CI 2.3–27.8). Caveats: a small trial below its planned sample size (88 per group), and participants could not be blinded, so expectation bias is possible. Funding: NHMRC grant; Woolworths food vouchers; Meat & Livestock Australia funded the biochemistry; the sponsors had no role in design or analysis. Open access, CC BY 4.0. - Firth J et al. (2019). The effects of dietary improvement on symptoms of depression and anxiety: a meta-analysis of randomized controlled trials. Psychosomatic Medicine 81(3):265–280. doi:10.1097/PSY.0000000000000673
16 RCTs, 45,826 participants (mostly non-clinical). Dietary interventions reduced depressive symptoms (g = 0.16); there was no significant effect on anxiety (g = 0.09). - Lally P, van Jaarsveld CHM, Potts HWW, Wardle J (2010). How are habits formed: modelling habit formation in the real world. European Journal of Social Psychology 40(6):998–1009. doi:10.1002/ejsp.674
96 volunteers repeated a daily eating, drinking or activity behaviour in the same context for 12 weeks. The time to reach 95% of peak automaticity ranged from 18 to 254 days. Missing one opportunity did not materially affect habit formation.
Not medical advice. This site shares general information and summaries of published research. It is not a substitute for professional diagnosis or treatment. Exercise can help, and it works best alongside care from a qualified professional. Check with your doctor before starting a new exercise program, especially if you have a health condition.
Need to talk to someone now? You are not alone. Call or text 988 (988 Suicide & Crisis Lifeline, US), available 24/7. If you are in immediate danger, call 911.
How to cite this page: Exercise Is The Answer. "Magnify the Effects." https://exerciseistheanswer.com/magnify-the-effects.html (2026, accessed [date]). Research summaries link to the original DOIs.