- The South Beach Diet is separated into three distinct phases. Phase One is a heavily restrictive period, with intake of sugars and carbohydrates severely limited. Even vegetables and fruits are limited in this phase, as many contain naturally occurring sugars. This detoxification can be quite uncomfortable and plagued with cravings. In the later two phases the restrictions lessen, adding certain carbohydrates and sugars back to the diet in small increments; however, these are still only available in limited quantities.
- The South Beach Diet requires a distinct lifestyle. This can be difficult to achieve for a dieter who dines out often or favors foods that are carbohydrate- and sugar-rich. Without committing to the total change in eating habits, the dieter stands a strong chance of relapsing. This is especially an issue in households where not all members are participating in the diet. The dieter must often eat partial meals or completely different foods, making mealtimes more inconvenient.
- The changes in eating habits and lifestyle on the South Beach Diet are anything but convenient. The recipes included by Dr. Agatston in The South Beach Diet Cookbook take some time and effort to prepare, and while they may mimic many popular foods, creating these foods from scratch is both time-consuming and costly. While, as of 2009, there are still some South Beach-specific and general low-carbohydrate products available in stores, these have dwindled in popularity as the public has moved on to the next fad diet.
- The restrictions of the South Beach Diet may place the dieter at risk of compromising her nutrition. By increasing protein intake, the risk of creating a vitamin deficiency or mineral imbalance is also increased. The balance of the diet may also lead to deficiencies in certain essentials such as calcium, making the diet especially risky for women prone to osteoporosis. Finally, the diet's fat and cholesterol content may pose a health risk for certain dieters prone to cardiovascular issues.
- The South Beach Diet can be a very successful weight-loss regime for many people; however, without a lifetime commitment to the lifestyle change and eating habits, the weight that was lost will often return. This places a strain on the body and organs, and is an unhealthy process referred to as "yo-yo dieting". While the initial drop in weight on Phase One may be encouraging to dieters, this weight is water weight or muscle mass and not true weight loss, making it difficult to maintain if you deviate from the diet.
