Hard time proving I am the same person as seen in the passport photo taken 9 years ago

No idea if this would work, but you could collect a bunch of photos of yourself, preferably portrait photos, taken about once (or twice) a year from 2005 to 2015.

If the significant change happened inside of one year, you would need to collect more photos from that period, e.g. one photo per month.

Bonus: Put these chronologically in a book and flick through the pages to show the gradual change in your appearance.

This depends on the country you’re entering. Before my last passport expired, I did quite a lot of traveling with an old photo that looked quite different from me. South Korean (many entries) and South African officials didn’t bat an eye. Hong Kong gave me little difficulty aside from a little extra scrutiny. Where I had difficulty was China and the US (I hold a US passport). Chinese (three occasions) and American (once) officials both took considerable time to scrutinize the passport and eventually asked me for additional ID. Both Chinese and American officials accepted my US drivers’ license and admitted me. I waited until my passport was nearly expired before renewing it.

The point is that the amount of difficulty can vary considerably depending on which country you’re trying to enter.

This just happened to me about 1 hour ago in Aruba. I was told by the US immigration officials (at the remote preclearance outpost in Aruba) that my passport, drivers license, and work ID didn’t look like me. They were each of different vintages, but all between 8-12 yrs old. I do look different now (thinner, mostly – but only about 18 lbs) but what a frustrating experience. At a certain point, it’s just a judgement call and there’s not much to say to them other than that “yes, this is me”. It becomes comical at a certain point, because there’s just not much more to say after a certain point.

For me, I think the answer will be renewing my drivers license early, which is a simpler process than reviewing a passport. That way, I’ll at least have some solid secondary ID to show.

As the other answerers point out, the best thing to do is to renew your passport asap. You may also want to consider emigrating to Europe. You will then be subject to less passport controls, so if you keep on gaining weight, you won’t have this problem anymore. When I flew from Norway to Germany last year, it struck me that I had not shown my passport to anyone during the trip. The check-in was self service, at the security check you only had to show the boarding pass and there was no passport control point that I had to pass through, both in Norway and in Germany. When I left the airport in Germany, I was thinking that had I stayed in Norway and let someone else use my plane ticket, no one would have noticed anything.

As the other answers have already mentioned: get a new passport with current photograph ASAP.
Anything else is folly.

Give the Indian embassy in Oslo a call.
It might be possible they can issue a passport, so you don’t have to go back to India for one.
If they can’t do that they should be able to advice you on the best cause of action.

You are probably running into several acts and regulations here, both of the issuing and the visiting country, each with vague and legalese description of what to do and what not to do.

The most relevant legal text is in this particular case probably the Norwegian alien regulation (Utlendingsforskriften), which in § 4-12 states that when entering or leaving the Schengen area, each person must subject to a minimal check to determine the identity based on the shown travel documents:

Alle personer skal ved inn- og utreise gjennomgå en minimumskontroll
for å fastslå identitet på grunnlag av fremvisning av reisedokumenter …

This is the national implementation of the Schengen Borders Code, which in article 7 states:

All persons shall undergo a minimum check in order to establish their
identities on the basis of the production or presentation of their
travel documents.

For all practical purposes, this means that you are required to present a valid travel document suitable to determine your identity. If your appearance has changed so much, that it is difficult to recognize you on your passport photo, it is your responsibility to obtain a new passport. You may of course present additional documents like a UK residence permit or an Indian ID card or driver’s license, but even if these are official documents, they have in Norway the same legal significance as a golf club membership card.

When it comes to passports issued in Norway, the Norwegian authorities are even allowed to seize your passport if your visual appearance has changed, so that the passport photo doesn’t match anymore (Passport act, Passloven § 7e):

Passmyndigheten kan kreve passet innlevert dersom … dets
opplysninger ikke lenger svarer til innehaverens utseende.

Or roughly translated:

The passport authorities can require the passport to be returned if
… its content do not longer match the holder’s appearance.

Let’s reiterate:

• You had a problem with your current passport
• People were not accepting (or at least easily) other means of identification
• It seems you were just let go on that occasion because people had “better things to do”.

Even if by all laws your current passport (or other documents provided) should work, you already know that this didn’t much impress the immigration officers you had to deal with. And they seemed to be of the friendly kind. Imagine what happens if one of them had a bad day and time to deal with you.

Sometimes even when you are right, it may be useful to remove as many obstacles as possible, so:

Make your passport photo match your physical appearance, one way or another.

Get your passport renewed as soon as possible. It’s a cheap option compared with being denied boarding of a flight or entry to a country. Since it expires in less than a year, you were probably going to want to renew soon anyway, as some countries need 6 months of validity.

In the meantime I would recommend carrying several pieces of photo ID with you, showing your new appearance and matching up with your passport details.

I know your question is totally based on the Schengen area of Europe, and its controls; however, I read an answer to a different question and it included a synopsis of a FAQ on the U.S. Department of State website, which I will add here as well.

Do I need to take a new photo if I recently dyed my hair a new color or grew a beard?

New photos are only required if your appearance has significantly changed from what is in your photo. Growing a beard or coloring your hair would not constitute a significant change. If you can still be identified from the photo in your current passport or visa application, you do not need to apply for a new passport or submit a new photo for your visa application. However, you may have to apply for a new passport or submit a new photo for your visa application if you have:

• Undergone significant facial surgery or trauma
• Added or removed numerous/large facial piercings or tattoos
• Undergone a significant amount of weight loss or gain
• Made a gender transition

The acceptance of your photo is at the discretion of the U.S. passport agency where you apply for a passport or U.S. embassy or consulate where you apply for a visa.

For the US, you would definitely want to consider a new passport. While a beard (or lack of) would not be considered a significant change, they do consider having “undergone a significant amount of weight loss or gain” to be so.

People do change in time, this is a fact an no one can do anything about it unless you really stick to a strict life style. Considering that, you have two options:

1. An expensive quick solution: Renew your passport, even if it is not expired. I am sure I have seen passport renewal forms with a checkbox saying “due to change in looks” or something like that. So just change your passport with a newer photo.
2. A cheap long term option: Lose weight! so you will look the same as the photo in your passport 10 years ago!

I think the opposite is also known to happen (i.e. people getting through with another person’s passport based on a vague similarity). Photos just aren’t very reliable. It’s difficult to judge without seeing your picture but I would therefore expect that with full documentation (especially a UK residence permit, even without biometrics!) most border guards would in fact let you through more easily.

That won’t help you right now but the Schengen area is moving towards a biometric visa database that would make the photo less important (although even that might not be completely fail-safe for all I know).

But if the photo is so bad as to reliably create problems, I am afraid there is no other solution than renewing the passport.