Stating logical results with "de ahí que"
To explain the direct result of a situation or habit, you can use the connector de ahí que ("hence" or "that is why").
Because this phrase frames the result as a logical deduction of what was just said rather than a new declaration, the verb that follows de ahí que must always be in the subjunctive.
| His lifestyle is sedentary, hence he gains weight so fast. | Su estilo de vida es sedentario, de ahí que engorde tan rápido. |
| The work is stressful, hence mental rest is essential. | El trabajo es estresante, de ahí que el descanso mental sea esencial. |
| That habit is harmful, hence the doctor forbids it. | Ese hábito es dañino, de ahí que el médico lo prohíba. |
Using "de ahí que" in the past
When you talk about a cause and effect that happened in the past, the rule stays the same, but you must shift the verb after de ahí que into the imperfect subjunctive.
| He ate a lot of protein, hence he lost weight in a healthy way. | Él comía mucha proteína, de ahí que adelgazara de manera saludable. |
| He had a lot of stress, hence he suffered from insomnia. | Tenía mucho estrés, de ahí que sufriera de insomnio. |
Alternative connectors for health and habits
While de ahí que requires the subjunctive, other common result connectors like por eso ("that's why") simply declare the result as a fact and take the indicative.
| That dessert is very harmful, that's why you gain weight. | Ese postre es muy dañino, por eso engordas. |
When you want to add a secondary consequence or build upon a good habit, you can connect related ideas using no solo... sino que también... ("not only... but also...").
| Stress not only produces insomnia, but it also affects mental health. | El estrés no solo produce insomnio, sino que también afecta la salud mental. |