How do different calorie sources (carbs, protein, fat) affect our bodies?
First, here's a great resource to be "
Snack Neutral." Plug in your snack, plug in your activity level, and see if you can cancel out your calories.
Let’s say a 140 pound person needs 1900 calories a day to maintain his weight.
IF:
- All 1900 calories come from carbohydrates, this person would become overweight, still feel hungry, and would be deconstructing his own muscle fibers to avail protein for vital processes.
- All 1900 calories come from protein, this person will likely lose weight with serious kidney and liver problems.
- All 1900 calories come from fat, this person will likely become overweight with serious heart problems.
Did you know obesity is a problem not because of
over-nourishment, but rather
under-nourishment? Why? Carbohydrates are the least costly kind of food, followed by oils, with protein-rich foods trailing far behind. This is because of the scarcity of nitrogen (in protein), vitamins, and minerals relative to the abundance of carbon (in carbohydrates and fat) in food.
Obesity, with its strongest ally being poverty, is prevalent among those who are under-nourished in protein and fruits and vegetables. The chief concern among the poor is first, “Did you eat?” not, “Did you get enough fruits, vegetables, and protein?” The cheapest and easiest way for a poor person to eat is by consuming excess carbohydrates, usually processed with fat (i.e., chips, fries, donuts…). Again, if protein is missing from the diet, the body’s muscle tends to shrink away while fat reserves pile on. Muscle requires more energy to maintain than fat reserves do, so the person’s caloric requirements lessen. If caloric intake stays the same while requirements become lower, the fat accumulates even faster. Thus, obesity sets in.
How do carbohydrates, proteins, and fats affect the body?
· Some destinations for carbohydrates:
1. Energy and Carbon Dioxide
2. Fat production
3. Nucleotides in DNA and RNA
4. Hunger Signaling:
a.
Ghrelin is a hormone that the empty stomach secretes, signaling “Hungry!” Carbs quickly suppress ghrelin at first, but within 2-3 hours, ghrelin rises to a level that’s higher than normal, saying, “HUNGRY!”
b. Insulin, a hormone produced by the pancreas, is secreted when blood sugar is high. People with Type 2 Diabetes are resistant to insulin. Insulin increases the excretion of leptin, thereby indirectly signaling “Full!” Insulin tells the body to begin making fat out of the excess sugar.
c.
Leptin, a hormone secreted by fat cells, signals “Full!” This helps us maintain a stable weight. However, obese people are often resistant to leptin, ignoring its signals to stop eating.
Emotional stress can increase leptin, so that people who are stressed out tend to eat less.
· Some destinations for proteins:
1. Energy, Carbon Dioxide, Ammonia or Uric Acid
2. Enzymes that catalyze most bodily processes
3. Formation of antibodies for immunity
4. Gateways in cell walls for the passage of nutrients
5. Mucous production
6. Cell structure and shape
7. Muscles, hair, finger and toenails
8. Hunger Signaling: Proteins don’t suppress ghrelin quickly but rather do so gradually, keeping you fuller longer.
· Some destinations for fats:
1. Energy + Carbon Dioxide
2. Fat accumulation
3. Neural tissue
4. Cholesterol production
5. Hormone production
6. Cell wall maintenance and water retention
To maintain a healthy weight, there appears to be a need for some sort of balance between the three types of calorie sources, right? Let’s look at a few diet options:
1.
LOW CARB DIETS: Carbohydrates (sugars) are scarce within the body for energy, so protein and fat (both from the diet and from body tissues) are broken down and their hydrocarbons are used for energy (natural gas and petroleum are other examples of hydrocarbons that provide energy). However, since protein and fat are not carbohydrates, they’re made up of more than just hydrocarbons, and the leftover byproducts form ketone bodies which are further metabolized into uric acid (the main component of urine). High levels of uric acid are dangerous to those who have livers and/or kidneys that don’t function well, causing further damage to these sensitive organs that purge our bodies of toxins. The
American Dietetic Association’s position on this is clear. Avoid diets that allow unrestricted protein and fat while restricting carbohydrates. These tend to increase cholesterol especially if the fats consumed are saturated (and, to some extent, if there also is high cholesterol content).
2. ATHLETIC DIETS: Carbohydrates are the most efficient fuel for the body, since we humans are well equipped with fast-acting enzymes that break down the sugar chains in starches. We also have high-capacity intestinal absorption of the resulting free sugars (Ruminants like cattle absorb and metabolize proteins more efficiently than starches and sugars, since their true stomach receives post-fermentative products from the rumen, i.e., low carbohydrate, high protein material). Muscles and the brain primarily operate on energy from carbohydrates. Getting enough carbohydrates in the diet is important so that your body won’t have to break down its own muscles to provide itself with energy…sounds counter-productive to your workout goals, right?
- · How many carbohydrates do you need if you’re doing normal daily exercise? Multiply your weight by 2.3 for light exercise (30 min. walking, light weights, casual sports) or 3.2 for more moderate exercise (running, moderate weight-lifting, daily sports). A 140 lb person doing light exercise needs 322 grams of carbohydrates a day (1288 calories from carbs).
- · How much protein do you need? Multiply your weight by 0.55 (light exercise) or 0.8 (moderate). A 140 lb person that does light daily exercise needs 77 grams of protein a day (308 calories).
- · What about fat? Well, the ADA makes no quantifiable requirement for fat, other than asserting that it’s essential. A 140 lb person needs to eat about 1900 calories to maintain their weight, so that leaves about 300 calories for fat, which is necessary for appetite suppression and satiety, water retention, cell health (all membranes of cells and organelles are fat-based), and for delivering fat soluble vitamins such as A, D, E, and K. The best fats are from oils found in fish, nuts, avocados, olives, flax, and greasy (not grizzly!) beef. A gram of fat has 9 calories, so about 33 grams of fat would fit well into this diet.
3.
SEDENTARY DIETS: For those who do not have time to exercise, do not like to exercise, or are unable to exercise, the best choice is to modify the Athletic Diet and reduce the carbohydrate portion. By eliminating 200 calories worth of carbohydrates, a 140 lb sedentary person can maintain a healthy weight with about 1700 calories. This person isn’t burning off 200 calories a day in exercise that the 1900 calorie moderate exerciser is. We all need to consume about
10 calories per pound of body weight just to keep our heart pumping and everything functioning at that weight (supplying basal metabolism for 140 lb person = consuming 1400 calories of energy). A little more energy is required to process the food we eat (the more food eaten, the more energy required to process it), and more energy on top of that is required for any voluntary activity like writing, sitting up straight, and walking. I echo what the
American Dietetics Association says in not so many words: eating more calories and working out is a lot more fun and brings about results faster than restricting calories and sitting still!
Overall, for the
moderately active individual, about 2/3 of the calories in the diet are to come from carbohydrates, 1/6 from protein, and 1/6 is to come from fat.
Carbs make up quite a bit of this diet, right? Remember that fruits (and vegetables, but less so) are also sources of carbohydrates besides cereals and starches. They contain plenty of water and fiber to keep you satisfied while taking advantage of all the vitamins, minerals, and antioxidants they contain.
Now what to do for your healthy weight goals? Well,
don't use a scale to guide your weight goals. How do you know if 140 pounds are mostly lean muscle or flab?
Don't obsess over numbers. Caloric intakes of 1700 or 1900 are just loose guides; as the unique individual you are, you probably do not fit the average recommendation! Pay attention to the way your clothes fit and the way your body looks in the mirror in response to your diet and exercise routine, then make your own adjustments according to what you
Think about calories from carbohydrates, proteins, and fat.
(Unless otherwise cited, I've taken much of this information from
Fundamentals of Biochemistry: Life at the Molecular level (3rd Edition) by Voet, Voet, & Pratt (2008))
