ideal weekly weight loss

Nope, he's not full of it. Recommended safe weight loss is 0.5lbs to 2lbs per week. Those losing 5lbs plus are either very heavy or are doing unhealthy things. The heavier you are the more you can lose originally as you can sustain a larger deficit. That is only for a period of time though as the larger of a deficit you have the higher risk you have of losing muscle mass. Smaller people who lose that much weight are losing muscle in the process. Losing that much is not healthy. Losing quickly also leads to gaining the weight back after the "diet" is finished and it also leads to more loose skin.

The slower you take the weight off means you keep more muscle mass, you have a better chance of keeping the weight off and it allows your skin to shrink back better.

I'm not sure where you see a lot of people losing that much weight? Maybe in their first week or two of a new routine (water weight, etc), but weight loss tends to slow pretty quickly after that

Generally, if you have a lot to lose, you can lose 1-2 pounds a week healthily. As you get nearer to your goal, that number gets smaller. If your ticker is right and you're looking to lose about 35 pounds, I would think about a pound a week (averaged out over time -- there may be weeks where you lose more, and weeks where you lose nothing) is a great rate of weight loss. As you get closer to your goal, that will shift to more like a half pounds a week (or even less)

1 pound per week may be more realistic for you, especially since you aren't overweight . To lose 2 pounds you have to cut out 1000 calories.