For this post I have got a 2 parter. Couple of interesting questions:
1. Why do we regain weight so easily especially if we were formerly fat?
2. Is glucose (sugar) weakening our immune system?
The first question is a direct result this Mark Sisson post, so I have basically just simplified the message.
Ever wondered why it’s easier for a formerly fat person to regain the lost weight, especially when they were fat as kids? The answer as usual lies in our bio chemistry or how we got fat in the first place. There are 2 ways to get fat:
a. Hypertrophy – Your existing fat cells get bigger.
b. Hyperplasia – Entirely new fat cells are created.
To paint a very simple picture, vast majority of fat cells are created in early childhood and adolescence. During early infancy and between ages of 9-13 appear to be crucial stages for creation of new fat cells, so after that age you are pretty much stuck with number of fat cells your body has made. Now weight loss doesn’t remove these fat cells but rather pulls fat from existing ones, leaving empty cells behind. If you had 35% body fat and after a drastic lifestyle change involving diet and exercise you got it down to 15%, you still have same number of fat cells.
So, now you have 2 people who have exactly the same weight and body fat %, let’s say 20%. Individual A was a fat kid and a teenager and Individual B was lean all along. Individual A is a lot better now at age 35 and has an active lifestyle whereas Individual B is your typical desk jockey, makes his living by pressing keys on computer. They both are at same body fat % and both are serious now about maintaining their body fat %. The formerly fat person will always be at a disadvantage compared to the formerly lean person when it comes to maintaining weight. Not fair right?
To understand what’s going on, you will need to understand how Leptin hormone behaves. Our fat cells secrete leptin hormone and remember that body stores energy as fat. So leptin in a sense is an indicator of how much energy is stored in the body. So, if you have eaten a meal of good quality fats and moderate proteins (like you mostly should), once you have had enough to eat, your body or fat cells will start releasing leptin to let the brain know that we have had enough. ‘Hunting has been good’ so to say. Now the amount of leptin that is released depends on the fat mass % as well size of fat cells.
Individual A who has 20% body fat (formerly obese) has way more fat cells that are relatively empty compared to Individual B who also has 20% body fat but has relatively fewer fat cells that are fuller. So what ends up happening is that Individual A is releasing far less leptin compared to Individual B. So your brain is thinking you don't have enough energy saved. This stacks up the odds against formerly fat by increasing their appetite, making them less active and the fat cells have a ‘fat memory’ that are just dying to store fat when it becomes available. Phew. It’s like growing up in bad neighbourhood and you are at a huge economic disadvantage for rest of your life.
|Vitamin C and Glucose, brothers from same mother|
Could a sugar spike be weakening your immune system as well? Well, the answer is looking like a yes.
I remember listening to Mark Sisson and him mentioning that he clearly remembers couple of instances when he fell sick and that sick day was preceded by consuming higher than usual carbs. I am not dying to repro the experiment by gorging on sugar but I would love to see some anecdotal evidence.It’s to do with relationship between glucose and Vitamin C at cellular level. If you don’t care about what is happening at cellular level, short story is that higher the levels of circulating glucose in the blood, the more difficult it is for Vitamin C to get into the cells and the more difficult it is to create immune cells. If you do care about cellular level details, read on.
Vitamin C is made naturally in nearly all living animals with notable exceptions being humans and primates. In mammals, the glucose is extracted from glycogen (stored sugar) and liver transforms it into vitamin C. Humans unfortunately lack an enzyme which is necessary for synthesis of Vitamin C and so we must get it from diet.
Vitamin C is important for building collagen (think bones, connective tissue) and promoting strong immune function. It turns out that Vitamin C and glucose may be competing for same receptors on the cells. They have very similar chemical structure and both rely on insulin signalling to get into the cell. This receptor is called Glut-1 and glucose has higher affinity to this receptor. So this means that if your meal has generated excessive levels of glucose, then Vitamin C may not be able to get into the cells. So what you say?
Remember our friends White Blood Cells? If you think hard enough about what you were taught one school day in your biology class, white blood cells are used to fight pathogens. Levels of Vitamin C in WBCs may be tens of times higher compared to other cells and they need 50 times more Vitamin C inside the cell than in the blood plasma to handle the oxidative stress – that is ingesting these pathogenic bacteria and virus.
It doesn’t stop here. Glucose and Vitamin C also seem to have opposite effect on creation of new immune cells or raw material for new white blood cells. If the immune system is under attack, it needs to quickly produce new white blood cells. If blood glucose is high enough, it will reduce the amount of new immune cells being formed.
Credit: Dr David Jockers has a great article on this topic.