Even when the fad diet pendulum swings back to its high carbohydrate/low fat phase, it is possible for dieters to eat too little fat for good overall health. For some impressionable dieters, fat in any form becomes the thing which must be avoided at all costs, since fat in the food is mistakenly believed to become fat on the body. Because of this irrational fear of dietary fat, some extreme dieters can easily eat too little fat to maintain vital body functions and processes.

Not all dietary fat is bad for the body, and even the government's own guidelines recommend that fats should constitute 30% of a person's daily caloric intake. For some dieters following an extreme high carbohydrate/low fat diet, the idea of consuming this much fat may sound counter-intuitive, but anything lower than a 20% daily intake generally means the dieter will eat too little fat to meet minimal guidelines.

The side effects of eating too little fat can be just as serious as consuming too much fat. The body may get a significant amount of energy from carbohydrates such as pasta, but it actually gets better fuel from essential fatty acids and lipids. If dieters eat too little fat, especially the good kinds like unsaturated and monounsaturated fats, they often lose a significant amount of energy throughout the day, and as a result their metabolism rates may slow, causing the body to store more fat, ironically enough.

When dieters eat too little fat, they may overtax the body's natural glycemic system as well. Fat cells help to keep blood sugar levels from spiking due to excessive carbohydrate and sugar consumption. Without a sufficient number of fat cells and fatty acids, dieters could send themselves into either hypoglycemic or diabetic spikes in blood sugar at unexpected times. When low or no-fat food substitutes are created, manufacturers must replace the fat grams with other ingredients, including sugars and other processed carbohydrates.

Some forms of fat are essential for the formation of healthy nerves and the repair of brain tissue. The body also needs some fat to form protective padding around joints, soles of the feet and palms of the hands. While it might be a good idea to cut back on the number of saturated and trans fats consumed every day, concentrating on fat grams to the exclusion of all other dietary considerations is not such a good idea. It is definitely possible to eat too little fat, and dieters should understand the differences between good fats, essential fatty acids and bad fats.