Question

Thoroughly discuss the current trend toward very low carbohydrate diets. Evaluate the safety and effectiveness of severely decreasing carbohydrate intake for weight management or other reasons. State your thoughts and reasons, citing evidence supporting your position.

Answer 1

current trend toward very low carbohydrate diet

A low-carb diet limits carbohydrates — such as those found in grains, starchy vegetables, and fruit — and emphasizes foods high in protein and fat. Many types of low-carb diets exist. Each diet has varying restrictions on the types and amounts of carbohydrates you can eat.

In general, a low-carb diet focuses on proteins, including meat, poultry, fish and eggs, and some nonstarchy vegetables. A low-carb diet generally excludes or limits most grains, legumes, fruits, bread, sweets, pastas and starchy vegetables, and sometimes nuts and seeds. Some low-carb diet plans allow small amounts of certain fruits, vegetables, and whole grains.

A daily limit of 0.7 to 2 ounces (20 to 60 grams) of carbohydrates is typical with a low-carb diet. These amounts of carbohydrates provide 80 to 240 calories. Some low-carb diets greatly restrict carbs during the initial phase of the diet and then gradually increase the number of allowed carbs. While very low-carbohydrate diets are often defined by the absolute amount of carbohydrate intake, usually less than 70 grams per day.

In contrast, the Dietary Guidelines for Americans recommend that carbohydrates make up 45 to 65 percent of your total daily calorie intake. So if you consume 2,000 calories a day, you would need to eat between 900 and 1,300 calories a day from carbohydrates.

There has been considerable debate about the metabolic effects of restricting carbohydrate intake in weight and diabetes management. However, the American Diabetes Association has noted that weight and metabolic improvements can be achieved with low carbohydrate, low fat (implicitly higher carbohydrate), or a Mediterranean style diet (usually an intermediate level of carbohydrate.

While very low-carbohydrate diets are often defined by the absolute amount of carbohydrate intake, usually less than 70 grams per day.

The metrics for evaluating the effectiveness of low-carbohydrate diets in the management of diabetes include weight, glycemia, cardiovascular risk indices, and other health indicators

low-carbohydrate diets may achieve better early weight loss than comparison diets higher in carbohydrate, but weight loss was comparable for studies that were one year or longer.(citation 1)

lower carbohydrate treatment condition resulted in lower A1c levels and lower doses of anti-diabetic medications than the higher carbohydrate comparison diet

There was significant reductions in triglyceride level on a carbohydrate restricted diet compared to 50-55% of energy from carbohydrate. The effects of carbohydrate restriction on LDL and HDL cholesterol appear to be indirect and largely modulated by the fatty acid distribution of fat intake.Nonetheless, carbohydrate restriction under weight-stable conditions has been associated with reduction in total HDL cholesterol ratio, apolipoprotein B, and the mass of small, dense LDL particles. These changes are similar to those achieved with weight loss without restriction of carbohydrate. (citation 2)

Low-carb diets may help prevent or improve serious health conditions, such as metabolic syndrome, diabetes, high blood pressure and cardiovascular disease. In fact, almost any diet that helps you shed excess weight can reduce or even reverse risk factors for cardiovascular disease and diabetes. Most weight-loss diets — not just low-carb diets — may improve blood cholesterol or blood sugar levels, at least temporarily.

Risks involved in low carb diet

If you suddenly and drastically cut carbs, you may experience a variety of temporary health effects, including:

• Headache
• Bad breath
• Weakness
• Muscle cramps
• Fatigue
• Skin rash
• Constipation or diarrhea

In addition, some diets restrict carbohydrate intake so much that in the long term they can result in vitamin or mineral deficiencies, bone loss and gastrointestinal disturbances and may increase risks of various chronic diseases.

Because low-carb diets may not provide necessary nutrients, these diets aren't recommended as a method of weight loss for preteens and high schoolers. Their growing bodies need the nutrients found in whole grains, fruits and vegetables.

Severely restricting carbohydrates to less than 0.7 ounces (20 grams) a day can result in a process called ketosis. Ketosis occurs when you don't have enough sugar (glucose) for energy, so your body breaks down stored fat, causing ketones to build up in your body. Side effects from ketosis can include nausea, headache, mental and physical fatigue, and bad breath.

It's not clear what kind of possible long-term health risks a low-carb diet may pose because most research studies have lasted less than a year. Some health experts believe that if you eat large amounts of fat and protein from animal sources, your risk of heart disease or certain cancers may actually increase.

If you follow a low-carbohydrate diet that's higher in fat and possibly higher in protein, it's important to choose foods with healthy unsaturated fats and healthy proteins. Limit foods containing saturated and trans fats, such as meat, high-fat dairy products, and processed crackers and pastries.

The 2012 ADA Standards of Medical Care state their precautionary recommendation as, “For patients on low-carbohydrate diets, monitor lipid profiles, renal function, and protein intake (in those with nephropathy), and adjust hypoglycemic therapy as needed.” The ADA rated the evidence level as “expert opinion” for this recommendation (citation 2)

Citations 1 Wylie-Rosett J, Davis NJ. Low-carbohydrate diets: an update on current research. Current diabetes reports. 2009 Oct;9(5):396–404. [PubMed] [Google Scholar]

Citation 2 https://www.ncbi.nlm.nih.gov/pubmed/18165339

Citation 3 American Diabetes Association Standards of Medical Care in Diabetes. Diabetes care. 2012 Jan;35(Suppl 1):S11–S63.