You seem pretty expert so-
I'm not a certified nutritionist or any other kind of expert, but I've spent 10 years studying metabolism, meal plans, structured diets, and exercise plans. I'm happy to give you my opinions, but that's all they are.
Packets here recommend 20g of saturated fat daily. Is there a problem not getting that?
If there are no weight problems is it okay to indulge the "good" fats?
I think you mean they recommend not having more
than 20g saturated fats daily. Here's the math for a 2000 cal/day diet.
Limit total fats to 30% of your daily intake.
Limit saturated fats to 7% of your daily intake.
Fat has 9 cals/gr. So 30% of 2000 cals is 600 cals or approx 67g fat/day. 7% of 2000 is 140 cals or approx 16g saturated fat/day. The numbers would go up to 80g fat/day and approx 19g saturated fat/day for a 2400 cal/day diet. This is considered a low-fat diet.
The problem with having more than 30% of your daily calories coming from fat is, well, you get fat. If more than 7% of your daily calories comes from saturated fat then they tend to find resting places in your arteries, around your organs, and generally slog everything down from running the way they should.
By all means indulge in good fats. The body is unable to manufacture omega-3s and omega-6s. The are known as essential fatty acids and are necessary for proper nutrition. They must be consumed through food sources or as supplements. Fortunately, omega-6s are easily consumed through cooking oils and other food oils such as nuts and avocados. Olive, corn, canola, safflower, sesame, sunflower, and nut oils are excellent sources of omega-6s. The nut oils also have some omega-3, but they are higher in saturated fats as well. Omega-3s are found in fish, flax (linseed), and nuts. Avocados and nuts pack a lot of fat for the buck, so eat sparingly but do indulge.
The other reason to include quality fats in your diet is because fats are satisfying. This is why most diet plans now recommend low-fat versions of dairy over fat-free versions and they no longer recommend trying to eliminate fats from your diet. If you are avoiding fats then chances are you're going to get hungry faster and eat other things to satisfy cravings. This usually means sweets or other carbs that will trigger blood glucose spikes sending you back to the pantry for more.
Can cholesterol levels be too low?
Low cholesterol isn't anything I've ever had to worry about personally but this
article from the Mayo Clinic discusses the risks of not having enough cholesterol.
What do you think of Quorn?
I've never heard of it. Must be a UK thing... after reading a bit about it I think I'd skip it. I'm more of a whole food type.
Quorn is the leading brand of mycoprotein food product in the UK and a leading brand elsewhere. Mycoprotein is the generic term for protein-rich foodstuffs made from processed edible fungus.
Quorn is produced as both a cooking ingredient and a range of ready meals. Quorn is sold (largely in Europe but also in other countries) as a healthy food and an alternative to meat, especially for vegetarians. As it uses egg white as a binder, it is not suitable for vegans. wiki source
And a question that might not be in your field-
Can a heart by-pass improve sight. A friend has had a BP and is reading without specs now which she couldn't before.
Anything's possible, I suppose, but I've never heard of it. Not that I neccessarily would have heard about it, I don't know much about bypass surgeries.