Food cravings are the reasons we tend to cheat on our diets. In fact, 80% percent of diets fail because people give in to food cravings. Tackling these food cravings is the key to losing weight. The cravings give you a taste for unhealthy foods, instead of nutritious ones. Cravings can also lead to snacking, and snacking directly reduces the amount of fat your body can burn between meals.
Our brain controls our cravings by controlling hunger and satiety (feeling full). The hunger centre in the brain makes you feel hungry, encourages your body to store energy, increases fat storage, and decreases fat burning. The hunger centre also turns down the body’s metabolism of fat burning. The satiety centre makes you feel full, decreases fat storage, increases fat burning, and boosts your fat burning metabolism. The key is a healthy balance between the hunger centre and the satiety centre. The hunger centre of the brain responds to falling blood sugar levels, causing us to seek out food, particularly sweet snacks that will rapidly return our blood sugar levels to normal. When we eat the sugary food, our body releases insulin, which carries the sugar out of our bloodstream and stores it as fat. Our blood sugar drops again and the food cravings return, creating a viscous cycle.
Many weight loss diets recommend eating five to six small meals per day and advocate that this type of eating is key to weight loss and lowering cholesterol levels. Almost all diet books either base their recommendations on this principal or incorporate aggressive snacking as part of their program. Ironically, there is almost no science to support this type of eating.
The myth that frequent small meals were the key to weight loss likely arose from two sources. The first involved dietary studies performed in the late 1990’s that showed how frequent small carbohydrate meals could lead to more stable blood sugar and insulin levels along with lower cholesterol. That research was aimed primarily at diabetics, however, the concept spread rapidly to normal and then overweight individuals. The second source is research indicating that metabolic rate increased temporarily after a meal. This led to the concept that more meals would somehow “supercharge” the body and allow it to burn off fat. New research is available that disproves these theories.
Does the myth of frequent small meal eating really “supercharge” our metabolism? The answer is “no”. While it is true that there is a temporary increase in the metabolic rate associated with the ingestion, absorption and metabolism of food, it only amounts to about 10% of your calorie intake and is independent of meal size. Unfortunately, the frequent small meal option reduces your leptin levels, which actually lowers your metabolic rate! The persistent secretion of insulin with frequent eating causes an increase risk of insulin resistance and metabolic syndrome. For those on a diet, frequent small meals are offered as the answer to food cravings and satiety. That is a little like trying to get someone to stop smoking while allowing them to light up every time they are craving nicotine!
Normal human physiology is not designed for frequent small meals and remains essentially unchanged from that of our prehistoric ancestors. Humans are hardwired to be hungry and to store food away as fat. The two major hormones, insulin and leptin work together to manage fat stores. After a meal insulin rises for three hours, initially replacing glycogen stores and then shunting any extra calories into fat. As insulin levels fall we become able to access our fat stores as a source of energy. Eating another meal or snack at this point causes a further release of insulin, which not only inhibits our ability to burn fat but also acts as a strain on the pancreas. This secondary rise in insulin is more prolonged and when the cycle is repeated will eventually lead to hyperinsulinemia and insulin resistance, forerunners of metabolic syndrome.
Leptin is a hormone produced by fat cells to signal the brain that they are “full”. It switches off the “hunger centre” and increases metabolism. Leptin facilitates the shift to fat burning in muscle cells about three hours after a meal and during prolonged aerobic exercise. Frequent meals are known to cause leptin resistance, as well as an insensitivity to leptin in the brain and peripheral tissues. This resistance impairs your ability to burn fat, slows your metabolism and increases food cravings.
When using exercise to lose weight, fat is normally mobilized at two to five times normal with even moderate activity, mostly from the abdominal area. However, even a slight increase in insulin along with resistance to leptin shuts off this process and prevents any access to fat stores. Therefore, snacking effectively reverses any weight-loss benefits of your exercise program.
Disclaimer:
The information above is intended for informational purposes only. Always consult with your health care provider if this is suitable for you.
Alene Falomo, ND
