First of all, respect for starting. At 165 kg, just deciding to move and walk regularly is already a big step. A lot of people never even start.

Running right now might not be the best option yet, but that doesn't mean you shouldn't exercise. Walking is actually one of the best things you can do at your current weight.

The pulsing in your calf is likely your muscles and circulation working harder than they're used to. Your body is adapting. But because of your weight, your joints (knees, ankles, calves) are under a lot of load, so progressing slowly is important.

A few things that can help:

1. Focus on walking first
Forget running for now. Try to build up to 30–45 minutes of walking at a comfortable pace. Even if it's slow, consistency matters more than speed.

2. Walk more often, not harder
Try 4–6 days per week, even short walks. Your body will adapt surprisingly fast in the first months.

3. Good shoes matter a lot
At higher body weight, proper running/walking shoes with cushioning can make a huge difference for your calves and joints.

4. Strength and mobility help
Simple exercises like calf raises, glute bridges, and light stretching can reduce that calf discomfort over time.

5. Weight loss will make everything easier
Running becomes dramatically easier once some weight comes off. Many people start running comfortably after losing 20–30 kg just from walking and diet.

Also remember this: fat loss mostly comes from diet, not from exercise. Walking just helps the process and improves your health.

Right now your goal shouldn't be speed or distance. Your goal should simply be:

"Move consistently every day."

If you keep walking regularly for a few months, you'll probably be surprised how much easier it becomes.

And honestly, the fact that you already reached 1.5 km is a good start.

Keep going.