This is a great question, and it gets to the very heart of the Buddha's teaching. I must say, it is a very common point of confusion, often because of the mistranslation or misunderstanding that the 1st noble truth means "life is suffering," which isn't at all what the Buddha taught.

The key is in understanding what Upādāna means in the pañcupādānakkhandhā: Upādāna carries a double sense in the canon: (1) the act of grasping/appropriating and (2) the fuel/sustenance that keeps a process going (via the Buddha’s fire metaphor). In most contexts—especially the formula “pañcupādānakkhandhā dukkhā” and in Dependent Origination—the standard and clearest translation is “clinging/appropriation.”

Hence what the Buddha really meant is: "appropriated aggregates are suffering", meaning that suffering arises specifically from clinging (appropriation, or upādāna), which is rooted in making things "I" or "mine."

Here is a more thorough breakdown, drawing on the suttas.

1. What the Buddha Actually Defined as Dukkha

In his very first sermon, the Buddha laid out the Four Noble Truths. When defining the First Noble Truth (Dukkha), he listed examples like birth, aging, sickness, and death, and then gave a definitive summary.

“Now this, bhikkhus, is the noble truth of suffering: birth is suffering, aging is suffering, illness is suffering, death is suffering; union with what is displeasing is suffering; separation from what is pleasing is suffering; not to get what one wants is suffering; in brief, the five aggregates subject to clinging are suffering.”

— SN 56.11 (Dhammacakkappavattana Sutta)

Full text: https://suttacentral.net/sn56.11/en/bodhi

The key phrase is "five aggregates subject to clinging" (pañcupādānakkhandhā). He did not just say "the five aggregates are suffering." This distinction is the most important point.

2. "Aggregates" vs. "Clinging-Aggregates"

The five aggregates (khandha) are simply the components of our experience:

• Form (bodies, sights, sounds, etc.)

• Feeling (pleasant, unpleasant, neutral)

• Perception (recognition, labeling)

• Mental Formations (intentions, choices, habits)

• Consciousness (the knowing of the other aggregates)

These are just the processes of life. The problem—the dukkha—is the upādāna (clinging, appropriation, "taking up").

The suttas make this distinction clear. In the Cūḷavedalla Sutta (MN 44), the nun Dhammadinnā is asked what the Buddha calls "identity" (sakkāya).

“'Identity, identity,' is said, Noble Lady. What, Noble Lady, is said to be identity by the Gracious One?”

“These five constituents (of mind and body) that provide fuel for attachment, friend Visākha, are said to be identity by the Gracious One, as follows: the form constituent that provides fuel for attachment, the feelings constituent... the perceptions constituent... the (mental) processes constituent... the consciousness constituent that provides fuel for attachment....”

— MN 44 (Cūḷavedalla Sutta)

Full text (Anandajoti): https://suttacentral.net/mn44/en/anandajoti

Full text (Bodhi): https://suttacentral.net/mn44/en/bodhi

As this translation notes, upādāna doesn't just mean "clinging"; it also means "fuel" or "nutriment." When we identify, cling to, or appropriate the aggregates, we are fueling a process of "becoming" (bhava)—the ongoing creation of a "self" that experiences birth, aging, and death, which is the "whole mass of suffering."

To be clear, the Buddha distinguished aggregates vs aggregates subject to clinging in this way:

"Linked Discourses 22.48

5. Be Your Own Island

Aggregates

At Sāvatthī.

“Mendicants, I will teach you the five aggregates and the five grasping aggregates. “Grasping” is so central to the concept of the five aggregates that we rarely find the “bare” aggregates mentioned as here. To head off a misunderstanding, the purpose of this discourse is not to establish that an arahant has aggregates free of grasping, since this is not brought up at all. Rather, it is to clarify the nature of grasping in relation to the aggregates. Listen …

And what are the five aggregates? The five aggregates are the five “masses” or “conglomerates” or “categories” consisting of all instance of that type of phenomena. So far as I can tell, it was not a Vedic technical term. However, the Jains know khandha as a clump of more than one atom, namely a “molecule” (Tattvārthasūtra 5.5). It seems that, along with other terms of similar meaning (sakkāya and puggala; see notes to SN 22.22 and SN 22.105), it was vocabulary shared with the Jains, though used in different senses. I have not discovered anywhere where the five are grouped together as such, although in the Suttas people who are not Buddhists seem familiar with them.

Any kind of form at all—past, future, or present; internal or external; solid or subtle; inferior or superior; far or near: this is called the aggregate of form.

Any kind of feeling at all …

Any kind of perception at all …

Any kind of choices at all …

Any kind of consciousness at all—past, future, or present; internal or external; solid or subtle; inferior or superior; far or near: this is called the aggregate of consciousness.

These are called the five aggregates.

And what are the five grasping aggregates? The five aggregates are not presented as a catch-all category that encompasses all of reality, but rather five types of phenomena that provoke attachment, forming the basis of what we take to be “self”. Desire is what drives the formation of attachment, but it requires all the aggregates to function. Thus the “grasping” aggregates are numbered “five” after the hand that grasps.

Any kind of form at all—past, future, or present; internal or external; coarse or fine; inferior or superior; far or near, which is accompanied by defilements and fuels grasping: this is called the grasping aggregate of form. The text illustrates the noun “grasping” (upādāna) with the future passive participle “graspable” (upādāniya). I render it “fuels grasping” to capture the secondary sense of “fuel” for the fire (SN 12.52:1.2). This is the aspect of the aggregates that stimulate or provoke desire and attachment. The “grasping” itself is the desire and lust for the aggregates (SN 22.121). But desire only functions as part of a system involving all the aggregates, hence the aggregates are neither identical to nor separate from the grasping (SN 22.82:4.3). Elsewhere we find the past participle “grasped” (upādinna) as that which has been “appropriated” or “taken up” at birth (MN 28:6.4).

Any kind of feeling at all …

Any kind of perception at all …

Any kind of choices at all …

Any kind of consciousness at all—past, future, or present; internal or external; coarse or fine; inferior or superior; far or near, which is accompanied by defilements and is fuels grasping: this is called the grasping aggregate of consciousness.

These are called the five grasping aggregates.”"

Here’s how Bhikkhu Sujato renders the four āsavas and what each means, in plain English:

• kāmāsava → “defilement of sensual pleasures” (the pull toward sights, sounds, smells, tastes, touches and their fantasies). It fuels chasing gratification and underpins craving. (SuttaCentral)

• bhavāsava → “defilement of existence/becoming” (the urge to be or to go on being in particular states or realms; ambition to continue or upgrade one’s mode of existence). (SuttaCentral)

• diṭṭhāsava → “defilement of views” (clinging to speculative or identity-forming views, including “I am” notions, eternalism, annihilationism, etc.).

• avijjāsava → “defilement of ignorance” (not seeing the four noble truths, dependent origination, impermanence, not-self—hence taking what’s conditioned as worth clinging to). (SuttaCentral)

Sujato consistently translates āsava itself as “defilements” (he avoids older renderings like “cankers” or “effluents/taints”). You can see his usage in his translation of MN 2 (Sabbāsava Sutta, “All the Defilements”) and in listings like DN 33 (Saṅgīti Sutta) where the four are enumerated. (SuttaCentral)

For a succinct modern explanation of how these four operate (kāma, bhava, diṭṭhi, avijjā), see this short piece from Barre Center for Buddhist Studies (it matches the same four and their sense). (Barre Center for Buddhist Studies)

One-line summaries

• kāmāsava: the mind’s leak toward sensuality—keeps attention flowing out to pleasant sense data. (SuttaCentral)

• bhavāsava: the momentum of becoming/existence—keeps projects of “being someone/somewhere” going.

• diṭṭhāsava: the stickiness of views—keeps “I am this/that” stories glued in place.

• avijjāsava: the darkness of ignorance—keeps the whole loop running by not seeing things as they are. (SuttaCentral)

If you want the exact passages in Sujato’s wording, the live translations are here (rendered titles and section headings will show “defilements”):
MN 2 (Sabbāsava): https://suttacentral.net/mn2/en/sujato
DN 33 (Saṅgīti): https://suttacentral.net/dn33/en/sujato (SuttaCentral)

(Background note: other translators sometimes choose “taints,” “cankers,” or “effluents/outflows.” Sujato’s “defilements” is a clean, contemporary choice; regardless of the English, the Pāli category and its four members are the same.) (themindingcentre.org)

3. Why Are the Clinging-Aggregates Dukkha?

Because the aggregates themselves are impermanent (anicca) and not-self (anattā).

When you try to grasp, own, or identify with something that is fundamentally unstable and uncontrollable, the result is friction, stress, and suffering. You are clinging to a waterfall and expecting it to hold you up.

The Buddha explained this in his second sermon, the Anattalakkhaṇa Sutta:

“Bhikkhus, form is not-self... For if, bhikkhus, form were self, this form would not lead to affliction, and it would be possible to have it of form: ‘Let my form be thus; let my form not be thus.’ But because form is not-self, form leads to affliction, and it is not possible to have it of form: ‘Let my form be thus; let my form not be thus.’

...[The same is said for feeling, perception, formations, and consciousness]...

“What do you think, bhikkhus, is form permanent or impermanent?”

“Impermanent, venerable sir.”

“And what is impermanent—is it suffering or happiness?”

“Suffering, venerable sir.”

“And what is impermanent, suffering, and subject to change—is it fitting to regard that as: ‘This is mine, this I am, this is my self’?”

“No, venerable sir.”

— SN 22.59 (Anattalakkhaṇa Sutta)

Full text: https://suttacentral.net/sn22.59/en/bodhi

So, the aggregates themselves aren't inherently suffering in an absolute sense. It is the clinging to them as "me" or "mine"—in defiance of their impermanent, not-self nature—that is suffering.

4. The Fetter is the Clinging, Not the Senses or Objects

This is a crucial point. The suttas are surgical in their analysis. The problem isn't your eye, or the things you see. The problem is the desire and passion that arises between them.

"The eye is not the fetter of forms, nor are forms the fetter of the eye. Whatever desire & passion arises in dependence on the two of them: That is the fetter there.

...The intellect is not the fetter of ideas, nor are ideas the fetter of the intellect. Whatever desire & passion arises in dependence on the two of them: That is the fetter there."

— SN 35.191 (Koṭṭhika Sutta)

Full text: https://suttacentral.net/sn35.191/en/sujato

An Arahant or a Buddha still has the five aggregates. They still see, hear, feel, and think. But because they have ended upādāna (clinging/appropriation), those "sheer aggregates" are no longer a source of suffering.

Likewise, we see similar statements in Mahayana and Vajrayana Buddhism:

"My son, we are not bound by appearances; we are bound by our clinging to them."

— Tilopa to Naropa

"The five senses arising with their objects are unimpeded radiance.

What is born from not grasping at objects is the unborn basic state.

Attachment to appearances may be unceasing but reverse it: meditate naturally settled.

Empty appearances arising free from the intellect is the path of natural expressions.

Do not see appearances as problems, let go of clinging.

There will come a time when you will arrive in the valley of one taste meditation."

— Yang Gönpa

5. The Solution: Realizing Anatman (No-Self)

The way to end this suffering is to see through the illusion of the "self" that is doing the clinging. This is the realization of anattā. The nun Vajirā gave a famous analogy for this:

“Why do you believe there’s such a thing as a ‘sentient being’?

Māra, is this your theory?

This is just a pile of conditions,

you won’t find a sentient being here.

When the parts are assembled

we use the word ‘chariot’.

So too, when the aggregates are present

‘sentient being’ is the convention we use.

But it’s only suffering that comes to be,

lasts a while, then expires.

Naught but suffering comes to be,

naught but suffering ceases.”

— SN 5.10 (Vajirā Sutta)

Full text: https://suttacentral.net/sn5.10/en/sujato

There is no "charioteer" (self) driving the chariot (aggregates), and no self/Self within nor apart from the aggregates. There is just the empty process manifesting due to dependent origination. When this is seen clearly, the basis for "I-making" and "mine-making" collapses.

6. The End of Appropriation = The End of Suffering

When appropriation ends, suffering ends. This is happiness and liberation. The Buddha used a powerful simile in the Alagaddūpama Sutta (The Water-Snake Simile):

“Therefore, bhikkhus, whatever is not yours, abandon it; when you have abandoned it, that will lead to your welfare and happiness for a long time. What is it that is not yours?

Material form is not yours. Abandon it. ...

Feeling is not yours. Abandon it. ...

Perception is not yours. Abandon it. ...

Formations are not yours. Abandon them. ...

Consciousness is not yours. Abandon it. ...

“Bhikkhus, what do you think? If people carried off the grass, sticks, branches, and leaves in this Jeta Grove, or burned them, or did what they liked with them, would you think: ‘People are carrying us off or burning us or doing what they like with us’?”

“No, venerable sir. Why not? Because that is neither our self nor what belongs to our self.”

“So too, bhikkhus, whatever is not yours, abandon it; when you have abandoned it, that will lead to your welfare and happiness for a long time.”

— MN 22 (Alagaddūpama Sutta)

Full text: https://suttacentral.net/mn22/en/bodhi

This "abandoning" is the practice. It's not a physical abandonment, but an abandonment of the view that these things are "me" or "mine."

A glimpse of what this non-appropriative experience is like is given in the Bāhiya Sutta:

“Therefore, Bāhiya, this is how you are to train yourself:

“In the seen, there will be just the seen.

In the heard, there will be just the heard.

In the sensed2, there will be just the sensed.

In the cognized, there will be just the cognized.

This, Bāhiya, is how you are to train yourself.

Bāhiya, when it is like this for you –

In the seen, there is just the seen,

In the heard, there is just the heard,

In the sensed, there is just the sensed,

In the cognized, there is just the cognized –

Then, Bāhiya, there will be no ‘you’ in terms of this.

When there is no ‘you’ in terms of this,

Then there is no ‘you’ there;

When there is no ‘you’ there,

There is no ‘you’ here, or beyond, or in between.

Just this is the end of suffering.”

— Ud 1.10 (Bāhiya Sutta)

It is the realization that in seeing, there is just the seen, never a seer behind, and in hearing, only sound, never a hearer. No agent, experiencer, observer, doer, nor any substantiated objects to be found.

Read more for explanations on Anatman realization and how it liberates: https://www.awakeningtoreality.com/2012/09/great-resource-of-buddha-teachings.html

Also see: Appropriated Aggregates are Suffering