To address issue (a) eat a lot more of EVERTHING, lift heavy things, sleep well, and be consistent about it. As far as issue (b) goes: you should be asking if you're getting enough of the following nutrients:
Vitamin B12, Vitamin D3, Zinc, Carnosine, Omega 3 Fatty acids (especially Docosahexaenoic Acid), Saturated Fat, Cholesterol, CoQ10, Taurine, and Creatine.
All the nutrients listed above, except for taurine and creatine, cannot be synthesized by the human body. All are essential for the healthy development and maintenance of the brain, the neuro-muscular system, vital organs, and skeletal muscle. In nature, all of these nutrients are found almost exclusively in the bodies of animals. (Fun fact, spiders are nature's best source of taurine, cow vomit is a close second, more familiar and palatable cuts of meat come in third)
This is not me telling my Earth friendly, green, crunchy friends they need to eat animals. Not at all. Most of those nutrients can be synthesized (through horrifying unnatural chemical processes in a laboratory, then manufactured in Chinese factories for wholesale distribution worldwide, where by the time it finally arrives at your door in supplement form, it's been through more processing, exploited slave labor, and burning through fossil fuels in transit than anything I would personally want to have in my body)
(Fun fact #2, China is the world's lead manufacturer of taurine, producing over 3000 tons annually, without the use of spiders... as far as I know.)
I digress... If you don't eat animals, make sure you find a reliable source of those essential nutrients, because they don't grow on trees.
(Fun fact #3, many mammals including humans can slowly synthesize taurine in small amounts. Cats cannot. Cats allowed to hunt for themselves get their taurine from the animals they eat. However, since many brands of commercial catfood contain more indigestible corn than actual animals, in the USA, taurine is required by law to be added to all cat food to help prevent the untimely death of your beloved pets.)
Now, about that picture of Bambi eating Thumper up there... It might surprise a lot of civilized people to see a herbivorous animal eating another animal. But this sort of thing happens all the time. Most herbivores are actually opportunistic omnivores. Deer are lousy hunters, like so, so bad at hunting. So as we all know, they are biologically equipped for a life of eating plants which can't scurry away and hide. But like most animals, deer still require a list of essential nutrients their bodies can't synthesize which are not readily available in plants. So, when a deer stumbles upon an egg, or a baby bird that fell out of the nest... munch, chew, swallow, nutritional supplement the way nature intended!
Nature loves efficiency. And animals are the most efficient source of nutrients for most other animals.
In the last 4 months, I've seen no less than 12 vegan propaganda memes floating around the web promoting the myth that Gorillas are 100% vegan, so humans should be too. There are several problems with this claim:
(1) Gorillas are also opportunistic omnivores. In 1993, the Jane Goodall institute published their findings that Gorillas eat monkeys and other small mammals to supplement their diet of mostly vegetation. Since, much like humans, gorillas have a laundry list of essential animal nutrients that their bodies can't synthesize. So, small monkeys are basically a gorilla's version of a multivitamin.
(2) Humans cannot survive on a gorilla diet. We would starve to death. Even though gorillas eat a much higher volume of food than we do, our digestive tracts are not equipped to process raw vegetation like the great apes.
Of all the things that make humans stand out from other animals, I think the most fascinating of all is the one we usually take for granted: we must cook our food in order to make it efficient for digestion and assimilation. Think about eating a raw potato. Not very tasty, right? It's shouldn't be, because that's your body telling you it's not an efficient source of nutrients. Potatoes are virtually indigestible to humans in their raw form. You would poop out a pile of potato mush, largely unchanged at the chemical level. HOWEVER, cook that potato, and something magical happens, suddenly a small potato goes from giving you nothing, to offering 161 calories of pure energy, 37 grams of carbohydrates, 4.3 grams of protein, and five essential vitamins and minerals, all of which your body uses.
We're not completely unique in the fact that we must chemically alter much of our food before it becomes efficient for consumption. A lot of other animals (like our friends, the tasty taurine-rich spiders) predigest their food by injecting or secreting enzymes in/on it before eating. Humans just kind of stand out because our pre-digestion tends to be much more elaborate (and probably more delicious too)
(Fun fact #4: Different species of animals are capable of synthesizing different nutrients. Eg: humans can synthesize their own vitamin D, rodents can synthesize their own vitamin C, and so on. So the question of who needs to eat who in order to survive basically comes down to an elaborate mortal contest of rock paper scissors in which the losers become lunch)
The general message is that since gorillas are big strong herbivorous animals, that humans should eat the same kind of diet, with the implication that doing so will grant superhuman gorilla-like strength.
I already wrote at length about how most herbivorous animals, including gorillas, are actually opportunistic omnivores that will occasionally eat small helpless animals, insects, and eggs when they can find them to supplement their diets. But that's not the main issue I'm taking here:
Gorillas spend over 80% of their time sitting around eating leaves. They eat over 40 lbs of raw vegetation every day. If you did that you'd die of a bowel obstruction on the first day. And even if you were able to fit 40 lbs of stems and leaves in your guts every day (you can't) you would still starve to death. Humans can't even digest a gorilla diet, let alone live off one. Our intestinal tracts are way too small. Gorillas have a much longer large intestine, capable of breaking down and extracting nutrients from raw vegetation.
You might as well say: hey cows can put on a ton of muscle mass with a diet of hay, so I'm going to eat hay so I can get big like a cow!
Nope. You can't digest hay either.
About half of these memes say something snarky about gorillas getting enough protein from their diets. Gorillas can extract protein from the raw leaves of trees. You can't. (Especially not 40 pounds of leaves a day) There's no comparison there. Significant plant protein sources for humans come primarily from cooked/processed/pre-digested grains and legumes. Gorillas don't eat that stuff. Ever. Humans have to cook their food in order to get enough energy from the relatively small amount of it we're able to fit in our guts on a daily basis. Gorillas don't have that problem.
Furthermore, protein synthesis isn't even the most serious dietary issue: it's the laundry list of essential nutrients required for higher brain function that only come from animal sources. A much more pressing question than "where do you get your protein?" Is "where do you get your omega 3 fatty acids?" Those come from fish, by the way, and you can't function at 100% without them. You'll also notice that unlike gorillas, humans can swim, and the majority of the human population lives in costal areas (whereas gorillas live up in the mountains) Unlike every other primate, human body hair grows in an aqua-dynamic fashion to facilitate swimming and diving. Coincidence? It's almost like nature is trying to tell us something about where to get our food.
Guys, you are not gorillas. Stop pretending to be gorillas. No matter what you eat or how much you exercise, you will never be as strong as a gorilla. An average gorilla is 4 to 6 times stronger than the world's strongest man, and gorillas don't even work out. They have that kind of strength because of their unique physiology, not their ethics on feeding.
Another common theme of the gorilla memes centers around their large canine teeth. They insist that since gorillas are herbivorous, but have large canine teeth, that humans with their much smaller canine teeth should be extra super herbivorous. Gorillas use those long teeth for fighting other gorillas, by the way, usually for mating rights. Should human men go around biting each other to win our women too?
If you want to know what an animal can and should eat, look at it's guts. Human and gorilla teeth are relatively similar, but our digestive systems are radically different. Again, gorillas are equipped to digest 40 lbs of leaves a day, humans are equipped to eat one to three pounds of food a day on average. But since our caloric requirements are similar, human food has to be up to 40 times as nutrient dense as gorilla food. Meaning we have to cook most of it, and we need significant sources of fat, up to one third of our total caloric intake.
But Ramsey, gorillas are only like 4% different genetically from humans! Shouldn't we eat the same diet? No. Beavers are also about 4% genetically different from humans. That doesn't mean you can eat tree bark. That being said, you're also over 80% the same genetically as those plants you're eating. You share way more commonalities than differences with lettuce, that doesn't mean you can feed yourself via photosynthesis or draw minerals out of the soil by sticking your feet in the dirt.
Gorilla strength is the other popular topic of memes like this- specifically the idea that a vegan diet will result in greater strength gains than an omnivorous human diet. They will often make an appeal to vegan strong-man Patrick Baboumian as validation- ignoring the facts that (1) Baboumian won most of his strong man competitions before becoming a vegan (2) the dude eats 20,000 calories a day and uses performance enhancers and numerous nutritional supplements (3) he's a large, big boned, 275 lb man who works extremely hard in the gym to maintain his strength level.
While Baboumian (who has been a vegan for 4 years now) is a strong, gifted athlete who understands principles of diet, supplementation, and exercise- I have never personally met a physically strong long term vegan (quite the opposite in fact) And I worry about the masses who do not understand the principles of athletics who are being told that they too can lift refrigerators if they simply stop eating chicken and beef. It doesn't work that way. Yes you can be a vegetarian or vegan athlete- but you have to first be an athlete- you've got to eat, move, sleep, breathe, think, and live like an athlete. That requires a great deal more "doing" than "not doing". And again, if you skip out on animal nutrients, you have to supplement- it's not optional for an athlete.
An average adolescent female gorilla is already over 3 times stronger that Baboumian by doing little more than eating and sleeping. Why? Because of their unique physiology- starting with the bones. Gorilla bones are larger, thicker, and much more dense than humans. Their extra long arms and oddly angled backs are also positioned in such a way to serve as optimal pulling levers, granting gorillas the ability to climb with the same speed an Olympic sprinter can run. Their shorter, thicker legs, and thickly muscled cores in combination with a swing from their powerful arms allow gorillas to quickly leap to astonishing distances when necessary. Their strength is truly remarkable- and we will never be able to emulate it, no matter what we eat. Skeletal muscle strength starts with our skeleton. Our skeleton are built with generalist rather than specialist applications in mind: swimming, walking, running, climbing, jumping, fighting- with the exception of our specialization in fine motor movement with an emphasis on finger/thumb dexterity and hand/eye coordination- (which again, is dependent on higher brain function, which is dependent on essential animal nutrients, which is/was largely dependent on our ability to be semi amphibious)
Herbivorous animals are not vegans. They're not even strict vegetarians. Those are human ideas/socio-political movements/philosophies. Animals eat each other- even the herbivores.
Look, if you don't want to kill and eat animals, that's cool. No problem there. There are lots of reasons to justify living that way. However, gorillas eating leaves and stems all day long is not one of those reasons. If you think people shouldn't hurt animals then say that. That's honest. These gorilla memes are intellectually dishonest. They are misleading. They are lies. Let's not do that anymore.